Spinach Gratin

Bahan-bahan (8 porsi)

• 2 tablespoons minced onion (or shallot)
• 1 tablespoon butter
• 1 clove garlic (minced)
• ⅔ cup light cream
• 4 ounces cream cheese
• ⅛ teaspoon salt (or to taste)
• black pepper (to taste )
• 20 ounces frozen chopped spinach (2 x 10 oz packages, thawed and squeezed dry)
• ½ cup shredded Havarti cheese (divided )
• ¼ cup shredded Parmesan cheese (divided )
• 1 tablespoon Panko bread crumbs (optional)