The strawberry sauce can be made the day before so it has plenty of time to chill. Combine one pound of sliced fresh berries with 1/3 cup sugar and 1 tablespoon balsamic vinegar. You could choose to use lemon juice instead. Bring to a boil then reduce the heat to simmer. Cook for about 25 minutes uncovered until thickened. Transfer the sauce to a bowl or glass measuring cup. Cover with plastic wrap and chill for four hours or overnight.
Chocolate Cake
Preheat oven to 350 degrees F. In a large mixing bowl, whisk together the flour, cocoa powder, baking soda, salt and baking powder.
In a separate bowl, whisk together the sugar, sour cream, vegetable oil, eggs and vanilla. Pour the wet ingredients into the bowl with the dry ingredients. Use a rubber spatula to mix the batter together.
Pour in the cup of hot coffee. And stir until well combined. Pour the cake batter into a 9x13 nonstick cake pan. Bake for 30 - 32 minutes, just until a toothpick inserted into the center comes out clean. Allow to cool in the pan for 30 minutes.
Frosting
Meanwhile prepare the frosting. Use a hand or stand mixer to whip the cream cheese until smooth. Add the vanilla and powdered sugar and stir on low speed until combined. Gently stream the heavy cream into the bowl while the mixer is still running on low speed. Then slowly increase the speed to high and beat until stiff peaks form. You’ll probably have to scrape down the mixing bowl a couple of times with a rubber spatula during this process.
Evenly frost the top of the cake using an offset spatula with the cream cheese frosting. Then use a spoon to evenly dollop the strawberries and sauce overtop of the frosting. Cut into 12 slices and serve.