*Ingredients*
- 2 tablespoons butter
- 2 tablespoons all-purpose flour
- 1 cup milk or cream
- 1/2 cup grated cheese (optional)
- Salt and pepper to taste
*Instructions*
1. Melt butter in a saucepan over medium heat.
2. Whisk in flour to create a roux. Cook for 1-2 minutes.
3. Gradually add milk or cream, whisking continuously.
4. Bring mixture to a simmer and cook until thickened.
5. Add grated cheese (if using) and stir until melted.
6. Season with salt and pepper to taste.
This basic sauce can be customized with various ingredients, such as diced onions, garlic, or herbs, to suit your casserole recipe.