Prepare the Chocolate Cake Layers: Preheat your oven to 350°F (175°C). Grease and line three 8-inch cake pans.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt. Add the warm water, vanilla, oil, and vinegar, and mix until smooth.
Divide the batter evenly among the prepared pans. Bake for 20-25 minutes or until a toothpick inserted into the center comes out clean. Let cool in the pans for 10 minutes, then turn out onto wire racks to cool completely.
Make the Strawberry Cream: In a mixing bowl, beat the heavy cream, powdered sugar, and vanilla extract until stiff peaks form. Fold in the strawberry jam and chopped strawberries.
Assemble the Cake: Place one chocolate cake layer on your serving plate. Spread a third of the strawberry cream over the cake, then top with a layer of fresh strawberries.
Repeat with the remaining cake layers and strawberry cream, ending with a layer of strawberry cream.
Prepare the Chocolate Sauce: Heat the heavy cream in a small saucepan over medium heat until it begins to simmer. Remove from heat and add the chocolate chips. Let sit for 5 minutes, then stir until smooth.
Let the sauce cool slightly, then pour over the top of the cake, allowing some to drip down the sides.
Decorate: Arrange fresh strawberries on top of the cake for decoration.
Chill: Refrigerate the cake for at least 1 hour before serving to allow the layers to set.