Creamy Onion Chicken Bake with Bell Peppers and Mushrooms

Ingredients

• 4 boneless, skinless chicken breasts
• 4 large onions, thinly sliced
• 1 red bell pepper, sliced
• 1 yellow bell pepper, sliced
• 7 ounces (about 2 3/4 cups) mushrooms, sliced
• 1 garlic clove, minced
• 2 tablespoons butter
• 3/4 cup heavy cream
• 1/2 cup grated cheese (optional, for topping)
• 1 tablespoon all-purpose flour
• 1 cup chicken broth
• 1 teaspoon dried thyme
• Salt, to taste
• Black pepper, to taste