To prepare jam, mix all ingredients in a small bowl and bring to a boil. Reduce heat and simmer until mixture begins to thicken, about 2 minutes. Remove from heat. Let cool completely.
To prepare cake, preheat oven to 350F. Grease three 5-inch cake pans and line bottoms with parchment paper. Set aside.
In a large bowl, mix together sugar, flour, cocoa powder, baking powder, baking soda and salt.
Crack in the egg, spoon in the sour cream, and pour in the oil and the vanilla. Mix with a wooden spoon until just combined.
Pour in the boiling water, and slowly mix until smooth and liquidy.
Divide batter evenly among the prepared cake pans. Bake for 18 to 20 minutes. Remove from oven and let cakes cool completely.
Run a pairing knife around the edge of the cake to loosen it from the pan. Peel off the parchment paper circles.
To prepare buttercream, beat butter for a few minutes in a standing mixer with the paddle attachment on medium speed. Add powdered sugar and turn the mixer on low, beat until the sugar incorporates with the butter. Add vanilla, heavy cream and cocoa powder, beat on medium speed for another 3 minutes, or until buttercream becomes light and fluffy.
To assemble the cake, fill a pastry bag attached to a 1/2″ round tip with buttercream. Place one cake layer on your serving plate, pipe a dam around the edge of the cake layer. Spoon 3 tablespoons of the jam inside the dam. Place another cake layer on top and repeat the same process. Place the last layer of cake on top. Smear a light coating of frosting on the top and sides of the cake. Cover and chill for 30 minutes.
To prepare ganache, place the chocolate and heavy cream in a medium heatproof bowl over a pot of simmering water. Stir the mixture using a wooden spoon until melted and smooth. Let cool slightly.
Remove cake from the refrigerator. Pour ganache over the top of the cakes. Use an offset spatula to gently push the ganache over the sides of the cake to create the dripping effect.
Decorated with fresh strawberries and pomegranate arils.
Cover and refrigerate the cake. Leave cake in room temperature for an hour before serving.