This is something I will make when I don't know what else to make and I usually always have the ingredients on hand. Here's what you do.
1 pound lean ground beef or turkey
1 small yellow onion
1 large jar of spaghetti sauce (I like to use Newman's Own Marinara)
1 pound spaghetti
2 cups shredded cheese (can use one kind or mix and match)
desired herbs and spices
Preheat oven to 350 degrees. Finely chop onion and brown in pan with ground meat until thoroughly cooked through. While it is cooking, boil the spaghetti until al dente (usually 8-10 minutes). Drain grease from pan. Stir in jar of spaghetti sauce and 1 cup of cheese. (I used cheddar and parmesan for the one pictured above). Add any desired herbs and spices to taste. Combine meat and spaghetti mixture with noodles. Pour into 9 X 13 casserole dish. Top with remaining cheese and bake for 30 minutes or until cheese is melted and bubbly. This is a very versatile dish so you can make a lot of changes to fit your preferences.