Pepper and Egg Brunch Bake - Got Milk

Ingredients

• 6 large eggs , beaten
• 3 cups milk
• 2 cups shredded Cheddar, Colby, or Monterey Jack cheese (8-ounce package)
• 1 teaspoon ground mustard
• 1/4 teaspoon salt
• 1/4 teaspoon freshly ground black pepper
• 6 cups cubed country-style sourdough or whole-wheat bread
• 1 13-ounce package turkey kielbasa , cut into 1/4‑inch pieces
• 1 1/2 cups chopped yellow onions (2 small)
• 1 cup chopped green bell pepper (1 medium)
• 1 cup chopped red bell pepper (1 medium)
• 1/4 cup chopped fresh basil
• Softened butter , for the baking dish