Step 1: Brown the Butter - Melt 226 g of unsalted butter over medium-low heat until it reaches a deep amber color, about 8–10 minutes.

Step 2: Mix Dry Ingredients - Preheat oven to 175°C (350°F), grease three 20-cm round cake pans, and whisk together flour, sugars, baking powder, baking soda, and salt.

Step 3: Combine Wet Ingredients - Whisk together buttermilk, eggs, and vanilla extract until smooth.

Step 4: Combine Ingredients - Blend the cooled browned butter with the dry mix, then gradually add the wet mixture and fold in chopped pecans.

Step 5: Bake - Distribute batter into pans and bake for approximately 30 minutes, or until a toothpick comes out clean.

Step 6: Cool Cakes - Let cakes cool in pans for 15-20 minutes, then invert onto racks to cool completely.

Step 7: Make Frosting - Beat together softened butter and cream cheese, then gradually add brown sugar, vanilla, salt, and confectioners' sugar, adjusting with heavy cream.

Step 8: Assemble Cake - Level cooled cakes, spread frosting between layers, frost the top and sides.

Step 9: Garnish - Sprinkle optional chopped pecans on top before chilling the cake.