Preheat your oven to 180°C (350°F).
Take 200 grams of unsalted butter and let it soften at room temperature. Mix in 1 tablespoon of finely chopped garlic, 1 teaspoon of mixed Italian herbs, and a pinch of salt. Set aside.
Slice a loaf of French or Italian bread into 1.5 cm thick slices, without cutting all the way through, leaving the base intact.
Spread the garlic butter mixture evenly on both sides of each bread slice.
Grate 200 grams of mozzarella cheese and 100 grams of cheddar cheese. Mix them together and stuff the cheese mixture between the slices of bread.
Wrap the stuffed bread loaf in aluminum foil and bake in the preheated oven for 15 minutes.
Unwrap the foil and bake for an additional 5 minutes, or until the cheese is melted and the bread is golden brown.
Remove from the oven, let it cool for a minute, and then serve.