Caramel layer cake recipe

Ingredients

• 2 sticks unsalted butter, softened, plus more for greasing
• 4 cups all-purpose flour plus more for dusting
• 2 Tbsp baking powder
• 2 tsp kosher salt
• ½ tsp baking soda
• 2½ cups sugar
• 1 vanilla bean, split and seeds scraped
• 4 large eggs
• 3 cups buttermilk

• 3 sticks unsalted butter
• 3 cups sugar
• 1½ cups buttermilk
• 1 Tbsp baking soda
• 1 tsp pure vanilla extract

Make the Cake
1. Preheat the oven to 350°. Butter and flour two 10-inch round cake pans and line the bottoms with parchment paper. In a bowl, whisk the flour, baking powder, salt and baking soda. In the bowl of a stand mixer fitted with the paddle, beat the 2 sticks of butter with the sugar and vanilla seeds at medium speed until fluffy, 3 minutes. Beat in the eggs 1 at a time until incorporated, then beat until very pale and billowy, 3 minutes. At low speed, alternately beat in the dry ingredients and buttermilk until just combined.
2. Divide the batter between the pans. Bake for 35 minutes, until the cakes are golden and a toothpick inserted in the centers comes out clean. Transfer to a rack; let cool in the pans for 30 minutes. Unmold the cakes, peel off the parchment and let cool. Place 1 cake layer on a cake stand or serving platter.
Make the Frosting
3. In a large, heavy-bottomed Dutch oven, melt the butter over moderately high heat. Stir in the sugar, buttermilk and baking soda. Cook, stirring constantly, as the mixture foams up, about 5 to 7 minutes. Continue cooking, stirring steadily, until the caramel mixture is very dark brown and reaches 240° on a candy thermometer, about 15 to 20 minutes. Carefully pour the mixture into the bowl of a stand mixer fitted with the paddle, add the vanilla and beat at low speed for 3 minutes, until thickened but still pourable. Use the frosting immediately.
4. Working quickly, scrape about 1 cup of the Caramel Frosting onto the cake on the stand and spread it to the edge. Top with the second cake layer. Pour the remaining frosting on top; quickly spread it over and around the cake to cover completely. Let the frosting cool for at least 2 hours before serving.