This oven baked 3-ingredient baked spaghetti casserole is one of those potluck miracles that everyone asks about. My neighbor brought it to a church potluck years ago, and it’s been stealing the show ever since. It tastes like something you fussed over all afternoon, but it’s really just spaghetti, jarred pasta sauce, and plenty of melty mozzarella baked together until bubbly and golden around the edges. It’s perfect for busy weeknights, feeding a crowd, or sending along to a new parent or neighbor who needs a comforting, no-fuss meal.
Serve this casserole hot with a simple green salad and some garlic bread or buttered rolls to soak up the extra sauce. A side of steamed green beans or roasted broccoli balances the richness nicely. For potlucks, I like to set it out right in the glass baking dish with a big serving spoon and let everyone help themselves, then offer grated Parmesan and red pepper flakes on the side for those who like a little extra kick.
Oven Baked 3-Ingredient Spaghetti CasseroleServings: 6-8
Ingredients
12 oz dry spaghetti
3 cups jarred marinara or spaghetti sauce (about 1 standard 24–25 oz jar)
3 cups shredded mozzarella cheese, divided
Directions
Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch glass baking dish so the spaghetti doesn’t stick.
Bring a large pot of salted water to a boil. Add the dry spaghetti and cook until just shy of al dente, about 1–2 minutes less than the package directions, since it will finish cooking in the oven. Drain the pasta well.
Return the drained spaghetti to the empty pot. Pour in 2 cups of the marinara or spaghetti sauce and 1 1/2 cups of the shredded mozzarella. Toss gently with tongs or two forks until the pasta is evenly coated and the cheese is mixed throughout.
Transfer the sauced spaghetti mixture into the prepared glass baking dish, spreading it out into an even layer and gently pressing it down so it fills the corners.
Spoon the remaining 1 cup of marinara sauce evenly over the top of the spaghetti. Use the back of the spoon to spread it out, leaving some little ridges and valleys for texture.
Sprinkle the remaining 1 1/2 cups of shredded mozzarella cheese evenly over the top, covering the surface so you get that bubbly, cheesy crust when it bakes.
Cover the baking dish loosely with foil, tenting it slightly so it doesn’t stick to the cheese. Bake in the preheated oven for 20 minutes, until the casserole is heated through and the cheese is mostly melted.
Remove the foil and continue baking for another 10–15 minutes, or until the cheese on top is fully melted, bubbling, and lightly golden in spots around the edges. This is what gives you that irresistible, picture-worthy top.
Let the casserole rest for about 5–10 minutes before serving so it can set up slightly and slice more neatly. Scoop into squares or big spoonfuls and serve straight from the glass dish while it’s still hot and cheesy.
Variations & Tips
For picky eaters, stick with a very smooth, mild marinara sauce so there are no visible chunks of tomato or herbs to fuss over. If your family likes a little more flavor but you still want to keep it simple, use a garlic- or basil-forward jarred sauce. You can also switch up the shape of the pasta: use penne or rotini instead of spaghetti if that’s what you have on hand, just keep the amount the same. To stretch the casserole for a bigger crowd, serve it with extra sauce warmed on the side so each person can spoon more over their portion. If you’re making this ahead, assemble the casserole, cover tightly, and refrigerate up to 24 hours; when baking from cold, add about 10 extra minutes covered before uncovering to brown the cheese. For a slightly crispier top, move the dish under the broiler for 1–2 minutes at the very end, watching closely so the mozzarella bubbles and browns without burning. Leftovers reheat well in the oven, covered with foil, or in the microwave with a splash of extra sauce to keep everything moist.
