Slice scallops thinly and marinate with olive oil, salt, and pepper for 10 minutes.

Slice garlic, chop onion, broccoli, and cauliflower into bite-sized pieces, and blanch them in salted boiling water.

Heat a pan with olive oil, sauté garlic, onion, and scallops, then add blanched broccoli and cauliflower. Season with salt and pepper.

In a pan, melt butter, add flour, and cook for 3 minutes until fragrant. Gradually add milk, stirring to prevent lumps, then mix in mozzarella and cheddar cheese to create the cheese sauce.

Layer cheese sauce, sautéed scallops and vegetables, more cheese sauce, mozzarella cheese, cheddar cheese, and parsley in an oven-safe dish.