Preheat your oven to 400°F (200°C). Peel the garlic cloves and place them in a small oven-safe dish, drizzling with olive oil and sprinkling with salt. Cover with foil and roast for about 20 minutes.

While the garlic is roasting, slice the chosen bread loaf in half lengthwise. Place on a baking sheet cut side up and pre-bake for 5 minutes.

In a mixing bowl, mash the roasted garlic until smooth. Combine it with melted butter, egg (if using), milk, salt, paprika, and parsley. Whisk until creamy.

Dip each half of the bread into the garlic butter custard until thoroughly coated. Allow excess custard to drip off before placing back.

Return the coated bread halves to the oven and bake for 15-18 minutes, or until edges are golden and crispy.

Remove and sprinkle mozzarella cheese over the hot halves. Switch to broil and return to the oven for 1-3 minutes until the cheese is melted.

Let cool for a minute, slice into pieces, and serve warm.