Preheat oven to 350°F (175°C). Grease two 8-inch round cake pans and line with parchment. Whisk flour, cocoa, sugar, baking powder, baking soda, and salt. Add eggs, buttermilk, oil, and vanilla. Beat 2 minutes. Stir in boiling water until smooth.

Divide batter between pans. Bake 25 to 30 minutes until a toothpick has a few moist crumbs. Cool in pans 10 minutes, then turn out onto a rack to cool completely.

Beat softened butter until creamy. Gradually add powdered sugar on low, then mix in strawberry powder, 2 tbsp cream, vanilla, and salt. Beat until fluffy, adding more cream if needed.

Place one cake layer on a plate, spread with about 1 cup frosting. Top with second layer. Frost top and sides with a thin crumb coat. Chill 15 minutes.

Place chopped chocolate in a bowl. Heat cream until simmering, pour over chocolate. Let sit 2 minutes, stir until smooth. Cool 5 to 10 minutes until it flows slowly from a spoon.

Pour ganache over the chilled cake, nudging it to drizzle down the sides. Let set 10 minutes, then slice and serve.