using fresh asparagus, trim the tough ends and cut into 2-inch pieces. For frozen asparagus, make sure it is fully thawed and drained to prevent excess moisture in the casserole.
Melt 2 tablespoons of butter in a medium saucepan over medium heat. Once melted, whisk in 2 tablespoons of flour and cook for 1–2 minutes to form a roux. Slowly pour in the chicken or vegetable broth while whisking constantly to avoid lumps. Add the heavy cream or milk and continue stirring until the mixture thickens slightly.
Remove the sauce
