Brown Butter–Buttermilk Cake

1. Prepare the Oven and Pan

Begin by preheating your oven to 350°F (175°C). Grease a 9-inch round cake pan with nonstick cooking spray or softened butter. If desired, line the bottom with parchment paper for extra security against sticking.

2. Create Brown Butter

In a small saucepan, melt ½ cup of unsalted butter over medium heat. Add the vanilla bean seeds or extract. Continue to cook the butter, stirring occasionally, until it becomes foamy and you see a golden-brown color at the bottom of the pan. This process, which takes about 5 minutes, enhances the butter's flavor to a rich, nutty aroma that will add depth to your cake.

3. Mix the Dry Ingredients

In a large bowl, combine the all-purpose flour, granulated sugar, light brown sugar, baking powder, baking soda, and kosher salt. Use a whisk to ensure that everything is evenly distributed and no lumps remain.

4. Prepare the Wet Ingredients

In a medium bowl, whisk together the buttermilk and eggs. If you’re using vanilla extract, add it to this mixture. Make sure the eggs are fully incorporated.

5. Combine the Batter

Pour the wet ingredients into the bowl with the dry mixture and add the browned butter. Gently whisk everything together until you have a smooth batter, taking care not to overmix.

6. Bake the Cake

Transfer the batter into the prepared cake pan. Place it in the preheated oven and bake for 35 to 40 minutes. To check for doneness, insert a toothpick or skewer into the center of the cake; it should come out clean when the cake is ready.

7. Cool the Cake

Once baked, allow the cake to cool in the pan for about 10 minutes before transferring it to a cooling rack. Let it cool completely before adding the icing.

8. Prepare the Icing

In a small saucepan, brown the remaining 2 tablespoons of butter over medium heat until it achieves that same golden hue and nutty scent, which should take about 4 minutes. In a separate bowl, whisk together the browned butter, confectioners’ sugar, and 2 to 3 tablespoons of buttermilk until smooth. Adjust the buttermilk quantity to reach your desired icing consistency.

9. Ice the Cake

Once the cake is completely cool, spread the icing over the top with a spatula. Allow it to set for 10 to 15 minutes.

10. Add the Finishing Touch

Finish by sprinkling flaky sea salt over the icing. This final touch adds a delightful contrast to the cake’s sweetness.