Squash Casserole Recipe: My Creamy, Crispy Sunshine Bake

Ingredients

• 2 lbs (900g) yellow squash, cut into ½-inch dice
• 1 medium yellow onion, chopped
• 1/4 cup (60ml) unsalted butter (57g)
• 1/4 cup (60ml) all-purpose flour (30g)
• 1 cup (240ml) whole milk
• 1/2 cup (120ml) sour cream
• 1/2 cup (57g) shredded sharp cheddar cheese
• 1/4 cup (50g) grated Parmesan cheese
• 1 large egg, lightly beaten
• 1 teaspoon salt (5g)
• 1/2 teaspoon black pepper (2.5g)
• 1/4 teaspoon garlic powder (1g)
• 4 tablespoons (60ml) unsalted butter (57g)
• 1 cup (100g) panko breadcrumbs
• 1/4 teaspoon salt (1g)
• 1/4 teaspoon black pepper (1g)