In a medium saucepan over medium heat, combine the chopped strawberries and sugar. Cook, stirring frequently, for about 4–5 minutes, until the strawberries begin releasing their juices
Stir in the lemon juice and continue to cook for another 2 minutes. Gently mash some of the strawberries with a spoon or potato masher to help break them down.
In a small bowl, stir together the cornstarch and water until smooth. Pour into the strawberry mixture and cook for another 1–2 minutes, stirring, until thickened.
Remove from heat and stir in the vanilla extract, cool completely. Reserve ¼ cup for the frosting.
Make the Cake Layers
In a small bowl or jar, stir together the apple cider vinegar and soy milk. Let sit for 5–10 minutes until it curdles slightly.
In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, salt, and sugar.
Add the vegan buttermilk, melted vegan butter, and vanilla extract. Beat on medium speed for 1–2 minutes until just combined. Scrape down the sides and stir again to ensure everything is incorporated.
Slowly pour in the hot coffee and whisk gently until the batter is smooth. Batter will be thin.
Preheat oven to 350°F (175°C). Grease and line three 8-inch (20 cm) cake pans with parchment paper.
Divide the batter evenly among the pans. Bake for 40 minutes, or until a toothpick inserted in the center comes out clean.
Cool the cakes completely in the pans before removing.
Make the Strawberry Buttercream Frosting
In a large bowl, beat the softened vegan butter until creamy. Gradually add powdered sugar and beat until light and fluffy.
Mix in the vanilla extract and reserved ¼ cup strawberry filling.
If the frosting is too thick, add 1 tablespoon vegan milk and beat until smooth and spreadable.
Make the Chocolate Ganache
In a small saucepan, heat the coconut cream just until steaming. Remove from heat and add the chopped chocolate. Let sit for 1–2 minutes, then whisk until glossy and smooth. Let cool slightly before using.
Assemble the Cake
If the cake layers are domed, level them with a serrated knife.
Place one layer on a serving plate or cake stand. Spread a generous layer of strawberry filling over the top.
Add the second cake layer and repeat with more strawberry filling.
Top with the final cake layer. Frost the entire cake with the strawberry buttercream.
Drizzle the cooled ganache over the top, letting it drip slightly down the sides.
Decorate with whole fresh strawberries.
Let the cake set for at least 1 hour before slicing.
Notes
Room temperature: Store this chocolate strawberry cake at room temperature for a day—and only if it’s not hot in your kitchen.
Refrigerator: Loosely cover the cake with plastic wrap or transfer leftovers to an airtight container. It will keep in the refrigerator for 3 to 4 days. (If you’re making this ahead for a party, I don’t recommend storing it for more than a day or two for maximum freshness.)
Freezer: It’s best to freeze the layers and filling separately if you’re freezing for advance prep. But if you’re freezing leftovers wrap the slices individually in plastic wrap, then place the slices in a freezer bag or airtight container. They’ll keep for up to 3 months; thaw in the refrigerator before serving.