Stuffed Tuscan Chicken

1 cup fresh spinach, chopped
½ cup sun-dried tomatoes, chopped
½ cup cream cheese, softened
½ cup shredded mozzarella cheese
¼ cup grated Parmesan cheese
2 cloves garlic, minced
For the Sauce (Optional but Recommended):

1 tablespoon butter
1 cup heavy cream
½ cup chicken broth
¼ teaspoon red pepper flakes (optional)
¼ cup grated Parmesan cheese
How to Make:

Prepare the Chicken: