Step 1

Preheat oven to 350 degrees F. Line the bottom of two 8-inch cake pans at least 2 1/2” deep with parchment paper or two 9” pans. Spray pans with nonstick cooking spray WITH flour or butter and flour pans.

Step 2

Sift together the flour, cocoa, baking powder and baking soda in a medium bowl. Whisk in sugar and salt ("dry ingredients"). Set aside.

Step 3

In a large bowl, whisk buttermilk, oil, eggs, and vanilla together until combined. Whisk dry ingredients into the wet ingredients just until combined. Whisk in boiling water just until combined, do not overmix (the batter will be thin).

Step 4

Evenly divide the batter between the cake pans and drop a few times on the counter to get rid of air bubbles. For 8” pans, bake at 350 degrees F 32-38 minutes, for 9” pans bake for 22-28 minutes OR until a toothpick inserted in the center of the cakes comes out with just a few moist crumbs (don’t open oven while baking or cakes could fall in center.)

Step 5

Cool cakes in pans for 10 minutes then transfer to a wire rack to cool completely before frosting. Once cool, level cakes if needed.

Step 6

Add raspberries (and any juices from thawing) to food processor and puree. Add puree to a fine mesh sieve over a bowl to discard seeds. Press down on the puree with the back of a spoon or spatula, until only seeds remain. This will take several minutes. Take care to wipe the back of your sieve to get all of the puree. You should end up with about 1 1/4 cups of puree.

Step 7

Add raspberry puree, cornstarch, sugar and lemon juice to a small saucepan. Bring to a simmer over medium-high heat, stirring constantly then reduce heat to medium (medium-low if your stove runs hot) and continue to cook and stir continuously until puree is thickened. Refrigerate until completely chilled.

Step 8

Do NOT start Ganache until your cakes are cooled because we will use part of it within 20 minutes to frost our cooled cakes.

Step 9

Add heavy cream to a large microwave safe bowl. Microwave until just boiling, about 2 - 3 minutes. Remove from microwave and add chocolate. Let stand 1 minute, then whisk vigorously until Ganache is melted and smooth. Whisk in 1 tablespoon corn syrup.

Step 10

Remove a heaping 1/2 cup Ganache to use in Chocolate Mascarpone. Let remaining Ganache stand at room temperature to cool until barely lukewarm, about 20 minutes OR until thickened but spreadable.

Step 11

Immediately after making Ganache, make Chocolate Mascarpone (so you can start assembling your cake before the Ganache cools completely).

Step 12

Using a handheld mixer, beat the mascarpone, cream, sugar and vanilla on low until no lumps remain. Add reserved heaping 1/2 cup ganache and increase speed to medium high and beat until thick, and stiff peaks form – should look like thick whipped cream. You don’t want to overbeat or the mixture will break and curdle but you want it quite thick.

Step 13

Cut cooled cakes in half horizontally using a long serrated knife to create 4 even layers. Place 1 layer, cut side up, on a serving plate or cake pedestal then evenly top with one third of your Raspberry Jam (about 1/3 cup). Top Jam with one third of your Chocolate Mascarpone (about 1 cup). Top with 2nd cake layer, cut side down, and repeat Jam and Mascarpone layers. Top with 3rd cake layer and repeat Jam and Mascarpone layers. Add final cake layer, cut side down.

Step 14

Separate out 1 cup lukewarm Ganache and frost top and sides of cake in a thin crumb layer. Freeze cake for 30 minutes to set Ganache. After 30 minutes, frost cake with desired amount of remaining Ganache. If Ganache is beginning to harden then add 1 teaspoon vegetable oil and microwave for 10 seconds then whisk. If it is too runny, then whip it with a hand held mixer to stiffen.

Step 15

Arrange raspberries in concentric circles on top of cake and dust lightly with powdered sugar. Serve with any remaining raspberries.

Step 16

If not serving immediately, assembled and frosted cake should be covered with an inverted bowl or cake cover and refrigerated. Bring cake to room temperature before serving (about 30 minutes on the counter).