1. Preheat your oven to 350 F (175 C). Using a sharp serrated knife, slice the sourdough loaf crosswise and lengthwise, creating a grid pattern. Make sure not to cut all the way through the bottom crust; you want to create pockets for the chocolate and butter mixture. A good visual cue is to stop about 1/2 to 3/4 inch from the bottom. Place the scored loaf on a baking sheet lined with parchment paper or foil.

2. In a small microwave-safe bowl, melt the unsalted butter. Once melted, stir in the granulated sugar, unsweetened cocoa powder, and vanilla extract until well combined and smooth. This mixture will be the base of our chocolatey goodness, seeping into every crevice of the bread.

3. Carefully open up the cuts in the sourdough loaf and spoon the chocolate butter mixture into all the crevices. Make sure to get it into both the crosswise and lengthwise cuts, aiming for even distribution. Don’t be shy; the more mixture you get in, the richer the final loaf will be.

4. Sprinkle the semi-sweet, milk, and white chocolate chips generously into all the cuts and over the top of the loaf. Try to distribute them evenly so every bite gets a mix of all three chocolates.

5. Transfer the baking sheet with the filled sourdough loaf to the preheated oven. Bake for 20-25 minutes, or until the bread is golden brown, the chocolate chips are melted and gooey, and the house smells incredible. If the top starts to brown too quickly, you can loosely tent it with aluminum foil.

6. Once out of the oven, if desired, warm the heavy cream slightly (either in the microwave or a small saucepan) and drizzle it over the hot loaf. This adds an extra layer of richness and a beautiful sheen. Let the loaf cool for a few minutes before serving to allow the chocolate to set slightly, making it easier to handle.