Preheat the oven to 350°F (175°C).
In a large bowl, combine the melted butter and minced garlic.
Add the bread cubes to the butter and garlic mixture and toss until the bread is evenly coated.
In a separate bowl, whisk together the milk, sour cream, Italian seasoning, salt, and black pepper until smooth.
In a 9×13-inch baking dish, spread half of the garlic butter coated bread cubes evenly.
Sprinkle half of the mozzarella cheese, half of the cheddar cheese, and half of the Parmesan cheese over the bread layer.
Pour half of the milk and sour cream mixture evenly over the cheese layer.
Repeat the layers with the remaining bread cubes, cheeses, and milk mixture.
Cover the casserole with aluminum foil and bake for 20 minutes.
Remove the foil and bake for an additional 10 minutes, or until the top is golden brown and the cheese is bubbly.
Remove from the oven and sprinkle chopped fresh parsley on top before serving.