Preheat the oven: Preheat your oven to 375°F and set out a large sheet of heavy-duty foil big enough to wrap the whole loaf.

Score the loaf: Using a serrated knife, cut the bread in a crisscross pattern about 1 inch apart, slicing three-quarters of the way down but stopping before you reach the bottom crust.

Make the garlic butter: Stir the melted butter, minced garlic, salt, and half the parsley together in a small bowl until fragrant and well combined.

Brush butter into cuts: Spoon or brush the garlic butter generously into every cut in the loaf, letting it drip down and pool at the base of each slice.

Stuff in the cheese: Tuck mozzarella slices and shredded cheddar down into each cut, pushing the cheese as far down as it will go so it melts throughout.

Add peppers: Sprinkle the diced red and green bell pepper over the top of the loaf, pressing some gently into the gaps between the cheese.

Wrap in foil: Wrap the entire loaf tightly in the foil, sealing the edges so steam stays trapped inside while it bakes.

Bake covered: Bake the wrapped loaf for 15 minutes, until the cheese has started to soften and melt inside the cuts.

Unwrap and finish baking: Carefully open the foil and bake uncovered for another 8 to 10 minutes, until the top turns golden and the cheese bubbles at the edges.

Garnish and serve: Remove from the oven, sprinkle with the remaining parsley, and serve warm so the cheese is still stretchy when pulled apart.