Preheat your oven to 350°F (175°C) and grease an 8x8-inch baking pan.

In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, and salt.

Add water, vegetable oil, vinegar, and vanilla extract to the dry ingredients, and stir until smooth.

Pour the batter into the prepared pan and bake for 30-35 minutes, checking for doneness.

Allow to cool in the pan for 10 minutes before inverting onto a wire rack to cool completely.

Beat softened cream cheese and unsalted butter until creamy, then gradually add powdered sugar and vanilla extract.

Slice the cooled cake horizontally into two layers and spread cream filling on the bottom layer.

Melt butter and heavy cream, stir in chocolate chips, then mix in powdered sugar and cocoa powder to make frosting.

Spread frosting over the assembled cake and decorate with sprinkles if desired.

Let sit at room temperature or chill before serving for clean slices.