To make homemade gravy, you’ll need butter, flour, and seasonings like salt, pepper, and onion powder. It all comes together in 15 minutes or less and can be made a day in advance.
Make a roux by adding equal amounts of butter and flour in a pot and adding milk, a little bit at a time, until blended. Stir constantly to avoid browning.
Beyond basic seasonings, add garlic powder, lemon juice, and herbs like parsley, dill, or thyme. To add some umami flavor, whisk in some chicken or vegetable broth.
You can also stir in grated parmesan or cheddar to melt into the sauce, saving some to go on top of the dish. Add the tuna, noodles, and veggies and bake in a casserole dish.