Preheat the oven to 350 and spray the bottoms of three 8-inch round cake pans with non-stick spray.
In a small saucepan, bring the buttermilk just to a simmer. Remove from the heat and stir in the cardamom, espresso powder and nutmeg. Let steep for about 15 minutes.
In a large bowl, whisk together the spiced buttermilk, brown sugar, eggs, oil and vanilla.
In a separate bowl, sift together the cake flour, baking powder, baking soda and salt. Add the dry ingredients to the wet and whisk by hand for about 1 minute, just until smooth and mostly lump-free.
Divide the batter between the pans and bake on the middle oven rack for about 22-25 minutes, until a cake tester comes out clean and the center of the cake springs back when lightly touched. Set the cake pans on a wire rack, cover loosely with a clean kitchen towel, and cool completely before frosting.