Preheat the oven to 350F. Butter 3 (9-inch) round cake pans or spray with baking spray and line the bottoms with parchment paper.

Into a medium bowl, sift the cocoa powder. Whisk in the hot water until the cocoa is dissolved. Let cool for 10 minutes.

Meanwhile, in a large bowl, whisk together the flour, sugar, baking soda, baking powder, and salt. To the cooled cocoa mixture, add the oil, buttermilk, eggs, and vanilla and whisk until well combined. Pour the cocoa mixture into the flour mixture and whisk until fully incorporated. Divide the batter among the cake pans.

Bake for 30 minutes or until the cakes are springy to the touch and just starting to pull away from the sides of the pan. Let cool completely in the pans. Run a knife around the edge of the cakes to loosen them and invert onto a wire rack. Remove and discard the parchment paper.

In a large mixing bowl or the bowl of a stand mixer fitted with the whisk attachment, beat the butter and a pinch of salt on medium speed until very light and fluffy, about 5 minutes.

Reduce the speed to low. With the mixer running, gradually add in the sugar, ½ a cup at a time, alternating with a tablespoon of the strawberries. Stop and scrape down the bowl a few times during mixing. Once the sugar is incorporated, beat on medium speed until light and fluffy, about 1 minute.

Place one cake layer on a serving plate. Top with ¾ cup of frosting and spread into an even layer. Top with another cake layer and another ¾ cup of frosting. Add the final layer and spread the remaining frosting all over the outside of the cake. Chill for at least 1 hour or up to 1 day.

Place the chopped chocolate in a medium heat-proof bowl.

In a small saucepan, heat the cream over medium-high heat just until simmering. Immediately pour over the chocolate and let stand for 5 minutes. Whisk together until the chocolate is fully melted and combined.

Spread over the top of the cake, letting some drip down the sides. Top with fresh berries. Chill and let the ganache set for at least 30 minutes before serving. Store the cake refrigerated for up to 5 days.