Instructions

To make the cake:

1. Preheat oven to 350°F. Grease 2 9-inch round cake pans. Line with parchment, and grease the paper.
2. Whisk together the flour, baking powder, and salt. Set aside.
3. Using an electric mixer on medium speed, beat the sugar, brown sugar, and butter until well mixed (about 5 minutes). Add the eggs, 1 at a time, beating well after each addition. Mix in the vanilla.
4. Reduce mixer speed to low. Add the flour mixture in three portions, alternating with two portions of the milk.
5. Divide the batter evenly between the prepared pans. Tap the pans on counter to remove any air bubbles. Bake 35 minutes, or until a pick inserted into the center comes out clean. Cool in the pans on a wire rack for 10 minutes. Remove from the pans and cool completely on wire racks.
6. Place one cooled layer on a cake plate.

To make the caramel:

1. Combine the brown sugar, milk, and butter in a heavy saucepan. Cook over medium heat until the sugar has dissolved. Cook, without stirring, until a candy thermometer reads 238°F. Transfer to a heat-resistant bowl. Beat 3 minutes or until thick enough to spread.
2. Immediately spread the caramel over the cake layer on the cake plate. Cover loosely with plastic wrap. Refrigerate until set (about 15 minutes).

To make the frosting:

1. Place the brown sugar and 4 tablespoons (56g) butter in a heavy saucepan. Cook and stir over medium heat until sugar has dissolved. Bring to a boil. Whisk in the cream and mix well. Transfer to a heat-resistant bowl to allow the caramel to cool to room temperature. Stir occasionally.
2. Using an electric mixer, beat 6 tablespoons (85g) butter and cream cheese on medium-high speed until smooth. Mix in the vanilla and salt.
3. While the mixer is still running, slowly add caramel and beat until smooth. Gradually add the confectioners' sugar, and beat until well combined. Chill the frosting until thickened for spreading. Stir occasionally.

To assemble the cake:

1. Spread a thin layer of frosting over the caramel filling. Place the second cake layer on top. Frost the top and sides of cake.
2. Chill until the frosting has set (about 20 minutes). Cover the cake and chill at least 4 hours. Let stand at room temperature for about 10 minutes before serving.