These soft and moist high altitude maple sugar cookie bars are studded with chopped hazelnuts, and frosted with a rich brown butter maple hazelnut frosting. They’re incredibly soft and chewy, and so addictive you won’t be able to eat just one. Top these maple blondies with a scoop of ice cream for a deliciously decadent dessert.
Looking for more recipes like this one? You might also love these s’mores chocolate chip cookie bars, frosted brown butter cookie bars, and gooey pecan pie bars.
Why You’ll Love This Recipe
Easy to Make. This is a simple recipe to make with standard pantry ingredients. You’ll love how easily and quickly the cookie dough comes together.
Perfect for Parties. I love to take cookie bars like these to parties and get-togethers. They stay soft and moist for days, so I can bake them the night before and frost them the next day. They disappear quickly!
Versatile. If hazelnuts aren’t your thing, you can easily substitute walnuts, pecans, macadamia nuts or even cashews.
See the recipe card at the end of the post for the full ingredients list and instructions.
Ingredients
Cookie Bars
- Butter. I use unsalted butter, but if you use salted, be sure to omit or reduce the extra salt in the recipe.
- Sugar. Adds sweetness and moisture.
- Eggs. Give the maple cookie bars structure and add moisture.
- Vanilla + Maple Extracts. Flavor.
- Flour. All-purpose flour gives the cookie bars structure and strength.
- Baking Powder. Leavens the cookie dough so it puffs up as it bakes.
- Salt. Balances the sweetness and enhances the flavor of the maple and hazelnuts.
- Hazelnuts. Gives the bars a nutty flavor and texture.
Frosting
- Butter. Brown the butter first to add a rich, nutty flavor to your frosting that’s irresistible.
- Powdered Sugar. Sweetens and thickens the frosting.
- Vanilla + Maple Extracts. Flavor.
- Salt. Balances the sweetness and enhances the flavor of the maple and hazelnuts.
- Hazelnuts. Gives the bars a nutty flavor and texture.
Instructions
Cookie Bars
- Preheat the oven to 350F. Line a 9×13 baking pan with a piece of parchment/baking paper and snip the corners so the paper fits down into the pan. Alternatively, you can use aluminum foil, and spray the foil thoroughly with non-stick spray.
- In the bowl of your stand mixer fitted with the paddle attachment (or using a bowl and hand-held electric mixer), beat the softened butter and sugar until light and fluffy, about 3 minutes.
- Add the vanilla and maple extracts, and mix in the eggs, one at a time, just until combined.
- In a separate bowl, whisk together the flour, baking powder and salt. Add the dry ingredients and the chopped hazelnuts, and mix the dough on low, just until moistened. The dough will be very thick.
- Pile the dough into the prepared pan. Since the dough is so thick and sticky, it can be a little tricky to spread it out. The best way is to butter your hands or a spatula and just push the dough out to the edges of the pan as evenly as you can.
- Bake the cookie bars on the center oven rack for about 20-22 minutes, just until the edges are set and every so slightly browned, but the center still looks a little underdone. Be careful not to over-bake these bars, or they will end up dry. They will continue to bake and set in the hot pan after you take them out of the oven. It’s normal for the center of the bars to settle and sink down a little as it cools.
- Set the pan on a cooling rack and cool completely before frosting.
Note: The baking pan I used in the photos for today’s post is slightly smaller than a 9×13 pan, measuring 8 1/2 x 11 inches. Since the bars were slightly thicker, I baked them for exactly 25 minutes.
Frosting
- To make the browned butter, melt the butter in a saucepan over medium heat. Continue to cook the butter for several minutes, swirling the pan occasionally, until nutty golden brown solids form at the bottom of the pan.
- Immediately remove from the heat and scrape the browned butter into a bowl. Let cool completely at room temperature, until the butter returns to a solid.
- Beat the cooled brown butter with an electric mixer for 1 minute until smooth.
- Add the powdered sugar, salt, vanilla and maple extracts. Beat for several minutes until very light and fluffy. Fold in the chopped hazelnuts (reserving a few tablespoons to sprinkle on top).
- Lift the cooled bars out of the pan by the paper, peel the paper off, and set the bars on a cutting board.
- Spread the frosting over the bars, sprinkle with rest of the chopped hazelnuts, and cut into bars.
Be sure to read all of my BAKING FAQs where I discuss ingredients, substitutions and common baking questions, so that you can be successful in your own baking!
Frequently Asked Questions
Can I skip the step of browning the butter for the frosting?
Yes, you can, but it’s a simple step that adds so much more flavor.
Will other nuts besides hazelnuts work in this recipe?
Any nuts will do, such as walnuts, pecans, macadamia nuts or cashews. All of these would be delicious in these maple cookie bars.
How long do these bars stay soft?
Leftover sugar cookie bars should be stored in an airtight container at room temperature for up to 3 days, or wrapped well and frozen for 3-6 months. They’ll stay soft and moist for days!
You Might Also Like
Hazelnut Orange Cake 
Chocolate Hazelnut Cake 
Maple Pecan Tart 
Sweet Potato Crumb Muffins
Favorite Products
Did you love today’s recipe? Please rate the recipe and let me know in the comments what you thought! Also, be sure to follow Curly Girl Kitchen on Instagram, and tag me when you try one of my recipes so I can see all your delicious creations!
High Altitude Hazelnut Maple Sugar Cookie Bars
All recipes on Curly Girl Kitchen are developed for high altitude at 5,280 feet.
Equipment
- Electric Mixer (Stand or Hand-Held)
Ingredients
Cookie Bars
- 1 cup unsalted butter, softened to room temperature
- 1 ⅓ cups granulated sugar
- 2 large eggs, room temperature
- 1 tbsp vanilla extract
- 1 tsp maple extract
- 2 ½ cups all-purpose flour, spooned and leveled
- 1 ¼ tsp baking powder
- 1 tsp coarse Kosher salt (if using table salt, use half the amount)
- ½ cup hazelnuts, roughly chopped
Frosting
- 1 cup unsalted butter, browned and cooled to a room temperature solid
- 1 ½ cups powdered sugar
- ¼ tsp coarse Kosher salt (if using table salt, use half the amount)
- 2 tsp vanilla extract
- 1 tsp maple extract
- ⅓ cup hazelnuts, finely chopped
Instructions
Cookie Bars
- Preheat the oven to 350F.Line a 9×13 baking pan with a piece of parchment/baking paper and snip the corners so the paper fits down into the pan. Alternatively, you can use aluminum foil, and spray the foil thoroughly with non-stick spray.
- In the bowl of your stand mixer fitted with the paddle attachment (or using a bowl and hand-held electric mixer), beat the softened butter and sugar until light and fluffy, about 3 minutes.
- Add the vanilla and maple extracts, and mix in the eggs, one at a time, just until combined.
- In a separate bowl, whisk together the flour, baking powder and salt. Add the dry ingredients and the chopped hazelnuts, and mix the dough on low, just until moistened. The dough will be very thick.
- Pile the dough into the prepared pan. Since the dough is so thick and sticky, it can be a little tricky to spread it out. The best way is to butter your hands or a spatula and just push the dough out to the edges of the pan as evenly as you can.
- Bake the cookie bars on the center oven rack for about 20-22 minutes, just until the edges are set and every so slightly browned, but the center still looks a little underdone. Be careful not to over-bake these bars, or they will end up dry. They will continue to bake and set in the hot pan after you take them out of the oven. It's normal for the center of the bars to settle and sink down a little as it cools.
- Set the pan on a cooling rack and cool completely before frosting.
Frosting
- To make the browned butter, melt the butter in a saucepan over medium heat. Continue to cook the butter for several minutes, swirling the pan occasionally, until nutty golden brown solids form at the bottom of the pan. Immediately remove from the heat and scrape the browned butter into a bowl. Let cool completely at room temperature, until the butter returns to a solid.
- Beat the cooled brown butter with an electric mixer for 1 minute until smooth.
- Add the powdered sugar, salt, vanilla and maple extracts. Beat for several minutes until very light and fluffy. Fold in the chopped hazelnuts (reserving a few tablespoons to sprinkle on top).
- Lift the cooled bars out of the pan by the paper, peel the paper off, and set the bars on a cutting board.
- Spread the frosting over the bars, sprinkle with rest of the chopped hazelnuts, and cut into bars.
I made these today. First time making brown butter! These are ALL about the frosting. So delicious and fluffy. Worked perfectly for me at 7500’
I’m so glad you love them! I took them to a party and they completely disappeared. 🙂
Amazingly good! Will definitely be on my treat rotation. I love your site! Finally success in cooking at high altitude!!!
Made these this weekend and they are amazing!!! Just an FYI, chopped hazelnuts are listed as an ingredient for the dough, but there is no mention of adding them to the dough in the instructions.
I’m so glad you love them! Thanks for letting me know about the typo – I’ve fixed that now. 🙂
If I don’t live in a high altitude area does the recipe need to be adjusted in any way? They look amazing! Looking forward to trying this ❤️
Kathy, these will probably work as is at low altitude too, but you may want to increase the baking powder to 2 teaspoons to make sure they rise enough.
Do you think pure maple syrup would work vs. maple extract?
No, because maple syrup isn’t concentrated like maple extract is, so the flavor would be too subtle.