Ingredients:

  • 1 cup (2 sticks) unsalted butter, softened
  • 2 cups granulated sugar
  • 4 large eggs, room temperature
  • 1 teaspoon vanilla extract
  • 3 cups cake flour, sifted
  • 1 tablespoon baking powder
  • ½ teaspoon fine sea salt
  • 1 cup buttermilk, room temperature
  • 3 cups granulated sugar, divided (for frosting)
  • 1 cup water (for frosting)
  • 6 tablespoons unsalted butter, cut into pieces (for frosting)
  • 1 (12 oz) can evaporated milk (for frosting)
  • ¼ teaspoon salt (for frosting)
  • 1 teaspoon vanilla extract (for frosting)

Instructions:

  1. Preheat the oven to 350°F (175°C). Grease and flour three 8-inch cake pans; line the bottoms with parchment paper rounds.
  2. Cream the Butter and Sugar: In a stand mixer, cream the softened butter until light and fluffy (about 3 minutes). Gradually add the 2 cups of sugar and beat until the mixture is pale and voluminous (5–7 minutes).
  3. Add Wet Ingredients: Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract. Scrape down the bowl.
  4. Combine Dry Ingredients: Whisk together the sifted cake flour, baking powder, and salt in a separate bowl.
  5. Alternate Mixing: Add the dry mixture alternately with the buttermilk to the wet ingredients, beginning and ending with the dry ingredients (Dry-Wet-Dry-Wet-Dry). Mix only until just combined; do not overmix.
  6. Bake: Divide the batter evenly among the three prepared pans. Bake for 30–35 minutes, or until a wooden skewer inserted into the center comes out clean.
  7. Cool: Cool the cakes in the pans for 10 minutes, then invert cakes onto a cooling rack. Remove the parchment paper and allow them to cool completely (at least 1 hour) before frosting.
  8. Create Dry Caramel: In a large heavy-bottomed saucepan, spread 2 cups of the granulated sugar in an even layer. Cook over medium-high heat, allowing the edges to melt first. Slowly stir until all the sugar is dissolved and turns a deep amber color. Immediately wipe down the sides of the pan with a wet pastry brush to prevent crystallization.
  9. Add Liquids Carefully: Gradually and very slowly stir in the evaporated milk (it will bubble violently). Stir until the caramel is completely dissolved and the mixture is smooth.
  10. Add Remaining Ingredients: Stir in the remaining 1 cup of sugar, the butter pieces, and the salt.
  11. Cook to Soft Ball Stage: Place the candy thermometer in the mixture. Bring the frosting mixture back to a boil, stirring frequently, and cook until the temperature reaches 238–240°F (114–115°C). Remove immediately from the heat.
  12. Cool Slightly: Stir in the vanilla extract. Let the mixture cool, undisturbed, until it reaches 110°F (43°C). This takes approximately 15–20 minutes.
  13. Beat and Spread: Transfer the mixture to a stand mixer. Beat on medium-high speed until the frosting lightens in color and is just thick enough to spread, but still manageable. Do not overbeat, or it will seize. Begin assembling the cake immediately.
  14. Spread generous amounts of the warm, spreadable caramel frosting between the cooled cake layers. Frost the top and sides quickly. Allow the frosting to set for at least 30 minutes before slicing and serving.