Prepare the Frosting: In a medium saucepan over medium heat, combine 190 grams of butter, 250 grams of semi-sweet dark chocolate chips, and 1 tablespoon of corn syrup. Stir continuously until completely melted and smooth, about 5 minutes. Remove from heat and cool in the fridge.

Preheat Oven: Preheat your oven to 170ºC (340ºF) and prepare three 20 cm (8-inch) cake pans by lining with parchment paper.

Make Coffee: Brew 360 grams of warm coffee or water and set aside to cool slightly.

Mix Dry Ingredients: In a large mixing bowl, sift together 360 grams of all-purpose flour, 2 tablespoons of cornstarch, 300 grams of granulated sugar, 150 grams of brown sugar, 75 grams of cocoa powder, 1.5 teaspoons of baking powder, 1.5 teaspoons of baking soda, and 1.5 teaspoons of salt. Whisk until fully combined.

Combine Wet Ingredients: In a separate bowl, whisk together 3 large eggs, 270 grams of sour cream, 165 grams of vegetable oil, 3 teaspoons of vanilla extract, and the cooled coffee. Mix until fully blended.

Combine Mixtures: Gradually pour the wet mixture into the dry ingredients, stirring gently until well combined and smooth. Avoid overmixing.

Pour Batter: Divide the batter evenly among the prepared pans. Bake in the preheated oven for 28-30 minutes, or until a toothpick comes out clean.

Cool Cakes: Once baked, cool in the tins for 5-10 minutes, then transfer each layer to a wire rack to cool completely.

Assemble the Cake: Level the tops if necessary, spread a layer of frosting between each layer, and coat the entire cake with the remaining frosting.

Decorate and Serve: Sprinkle chocolate chips on top, refrigerate for about 30 minutes to set frosting, cut into generous pieces, and enjoy!