Ingredients:
- 3 sticks butter, at room temperature, plus more for pan
- 3 1/2 cups flour, plus more for pan
- 1 tsp. baking powder
- 1/2 tsp. fine salt
- 2 cups packed light brown sugar
- 1 1/2 cups granulated white sugar
- 6 large eggs, at room temperature
- 1 1/2 cups whole milk, at room temperature
- For the icing:
- 1 stick butter
- 1 cup packed dark brown sugar
- 1/2 cup milk
- 1/2 tsp. pure vanilla extract
- 4 cups confectioners' sugar, sifted