Preheat the oven to 350F. Line a standard-sized muffin pan with 12 paper liners, or a jumbo muffin pan with 6 jumbo paper liners. Lightly spray the liners with non-stick baking spray.
In a bowl, sift together the flour, cocoa powder, corn starch, sugar, salt, baking soda and baking powder. Sifting is important, to get rid of the lumps in the cocoa powder.
Separately, whisk together the eggs, buttermilk, oil and extracts.
Add the wet ingredients to the dry, and whisk briefly just to barely combine, but with a few floury streaks remaining.
Add 1/2 cup chocolate chips and 1/4 cup chopped almonds to the batter, and fold in.
Divide the batter between the cups. Sprinkle the top of the batter with the remaining 1/4 cup chocolate chips and 1/4 cup chopped almonds.
Bake small muffins for about 18-20 minutes, and large muffins for 28-30 minutes, until a toothpick or cake tester inserted in the center comes out clean.
Cool 5 minutes in the pan, then transfer to a cooling rack to cool for 15 minutes. Serve warm.