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)

Instructions:

  1. Melt butter in a large skillet or Dutch oven over medium heat. Add squash and onion and cook until softened, about 8-10 minutes.
  2. Whisk in flour and cook for 1 minute. Gradually whisk in milk and cook, stirring constantly, until thickened, about 2-3 minutes.
  3. Remove from heat. Stir in sour cream, cheddar cheese, Parmesan cheese, egg, salt, pepper, and garlic powder.
  4. Melt butter in a separate skillet over medium heat. Cook, swirling constantly, until butter turns golden brown and smells nutty, about 3-5 minutes. Be careful not to burn. Remove from heat and stir in panko breadcrumbs, salt, and pepper.
  5. Pour squash mixture into a greased 9x13 inch baking dish. Sprinkle with brown butter breadcrumbs.
  6. Bake in a preheated oven at 350°F (175°C) for 25-30 minutes, or until golden brown and bubbly. Let cool slightly before serving.