Begin by melting the butter in a saucepan over medium-low heat, then increase the temperature slightly and cook until you see golden brown flecks appear, indicating the butter is browned. Set it aside to cool completely.
Preheat your oven to 350°F (175°C) and prepare three 8-inch round cake pans by greasing and lining them with parchment paper.
In a large mixing bowl, whisk together the cake flour, granulated sugar, light brown sugar, baking powder, baking soda, and salt until evenly combined.
Pour the cooled browned butter into the dry ingredients and stir until everything is thoroughly incorporated.
In a separate bowl, whisk the buttermilk, eggs, and vanilla extract together. Slowly add the dry mixture into the wet ingredients, mixing gently until just blended. Fold in the finely chopped pecans.
Distribute the batter evenly into the prepared pans and bake for about 30 minutes, or until a toothpick inserted in the center comes out clean. Allow the cakes to cool fully before frosting.
To make the icing, beat the softened butter, cream cheese, light brown sugar, vanilla extract, and salt until smooth and creamy. Gradually add the powdered sugar and heavy cream while continuing to beat until the frosting is light and fluffy.
If needed, level the cooled cakes. Assemble by spreading icing between each layer, then cover the entire cake with the remaining frosting. Garnish the top with additional chopped pecans and pipe decorative frosting swirls if you like.
