1. Brown the Butter: In a light-colored saucepan, melt the butter over medium heat. Continue cooking, stirring occasionally, until the butter turns a rich golden-brown color and nutty aroma fills your kitchen. You’ll see tiny brown bits forming at the bottom of the pan. This usually takes about 5-7 minutes. Immediately pour the browned butter into a heatproof bowl to stop the cooking process and let it cool slightly for about 10 minutes. This step is crucial for the cake’s distinctive flavor.

2. Prepare Dry Ingredients: While the butter cools, whisk together the all-purpose flour, baking powder, baking soda, and salt in a medium bowl. Make sure there are no lumps and the ingredients are evenly distributed. This ensures a consistent rise and texture in your cake.

3. Combine Wet Ingredients: In a large mixing bowl, cream together the slightly cooled brown butter and granulated sugar until light and fluffy. Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract and the sourdough discard until just combined. The mixture might look a little curdled, but that’s perfectly normal.

4. Alternate Wet and Dry: Gradually add the dry ingredient mixture to the wet ingredients, alternating with the buttermilk. Begin and end with the dry ingredients. For example, add about a third of the flour mixture, mix until just combined, then add half of the buttermilk, mix, then another third of the flour, the remaining buttermilk, and finally the last third of the flour. Be careful not to overmix, as this can lead to a tough cake. Mix until just combined and no streaks of flour remain.

5. Bake the Cake: Pour the batter into a greased and floured 9×13 inch baking pan or two 8-inch round cake pans. Smooth the top with a spatula. Bake in a preheated oven at 350 F (175 C) for 30-35 minutes, or until a wooden skewer or toothpick inserted into the center comes out clean. The cake should be golden brown and spring back when lightly touched.

6. Cool and Serve: Once baked, remove the cake from the oven and let it cool in the pan on a wire rack for at least 15-20 minutes before attempting to remove it. This allows the cake to set properly and prevents it from breaking. If using round pans, invert onto a wire rack, remove the pan, and then invert again onto another rack to cool completely right-side up. Once cooled, you can slice and serve as is, or add your favorite frosting.