Nothing fancy, no special piping, just an elegant unfrosted chocolate layer cake with a caramel drizzle. The appeal is universal. So bake it, take it to the party and then bask in the praise. You'll deserve it.
Heat oven to 350°F. Line bottom of two 8-inch round baking pans with parchment paper. Lightly butter pan sides and dust with cocoa.
Stir together chocolate chips and cocoa in heat-proof bowl. Add boiling water; stir until chips are melted and mixture is smooth. Set aside.
Sift together flour, baking soda, salt and baking powder in large bowl; set aside. Beat mayonnaise, granulated sugar and brown sugar in large bowl until well combined. One at a time, add eggs and egg yolk, beating after each addition. Beat in vanilla. Alternately add flour mixture and chocolate mixture, beating just until blended after each addition. Divide batter evenly into prepared pans.
Bake 25 to 30 minutes or until cake springs back when gently pressed and wooden pick inserted into cake center comes out clean. Cool completely in pans on wire rack.
Evenly divide and pour batter into prepared pan. Bake until the cake springs back when gently pressed and a toothpick inserted into the center comes out clean, about 20-25 minutes. Transfer to a wire rack to cool completely.
Prepare Vanilla Frosting. Remove cakes from pans. Slice each cake in the middle horizontally. Place one cake layer on serving plate; top with 1/4 inch layer of frosting. Repeat with remaining cake layers and frosting. Drizzle top with caramel topping. Cover; refrigerate leftover cake.
Beat butter in large mixer bowl until creamy. Beat in sea salt. Add 1 cup powdered sugar and 1 tablespoon milk, beating on low until combined. Increase mixer speed to high; beat until smooth. Repeat procedure, adding 1 cup powdered sugar and 1 tablespoon milk at a time. Blend in vanilla.
* The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet 2,000 calories a day is used for general nutritional advice.