This Spaghetti Squash Casserole is an easy vegetarian dinner packed with black beans, corn, fire-roasted tomatoes, cheddar cheese, and Southwest spices. The spaghetti squash keeps it lighter than a traditional pasta casserole while still making it hearty enough for dinner.
When I asked my readers recently what types of recipes they’d like to see more of, an overwhelming number asked for gluten-free recipes. Another big request was recipes that don’t have any meat. Given the prices of groceries, I get it.
In this tasty vegetarian casserole, you get both of those requests in one recipe your family will love. This recipe is easy to make and is full of delicious, familiar flavors. This is a dish that even meat-eaters will love!
Why This Recipe Works
- Hearty without meat: This vegetarian dish is substantial enough for a meal with black beans, cheese, and spaghetti squash.
- Loaded with Southwest flavor: Chili powder, cumin, smoked paprika, jalapeños, and fire-roasted tomatoes keep the casserole from tasting bland.
- Not watery: Draining the tomatoes and any excess liquid from the squash, avoiding overcooking the squash, and baking the casserole uncovered prevent a watery casserole.
- Naturally gluten-free and vegetarian: No substitutions needed.
Ingredients and Substitutions
- Spaghetti squash: Look for one that is around 2-2 1/2 pounds. Larger squashes will take longer to roast.
- Fire-roasted tomatoes: Be sure they are drained very well. Regular diced tomatoes can work, but fire-roasted will add more flavor.
- Black beans: Canned beans are packed in liquid. Rinsing and draining them well prevents excess liquid and salt from being added to the casserole.
- Corn: Frozen corn is added right to the recipe; no need to cook it or thaw it first.
- Cheddar cheese: Cheese grated from a block will melt and taste so much better than pre-shredded cheese.
- Jalapeño: Removing the seeds and ribbing keeps the heat mild.
How to Make Spaghetti Squash Casserole
- Cut the squash in half lengthwise and remove all of the seeds and pulp using a spoon. Coat the cut side with olive oil and season with salt and pepper. Place the cut side down on a baking sheet covered with parchment paper. Bake until just tender.
- While the squash is baking, sauté the onion, garlic, and jalapeño in a skillet with olive oil and the seasonings.
- Key step: Drain the tomatoes very well in a metal sieve over a bowl.
- Scrape the insides of the spaghetti squash into a large bowl. Drain off any water that has accumulated at the bottom of the bowl before adding the remaining ingredients. Add the onion and spice mixture, black beans, frozen corn, roasted tomatoes, and cheese. Stir to combine.
- Add the mixture to a greased baking dish and bake for 20 to 25 minutes or until the edges of the casserole have begun to brown and the cheese is fully melted.
How to Keep Spaghetti Squash Casserole From Getting Watery
- Avoid overcooking the squash: Overcooked spaghetti squash will be mushy and make your casserole watery. Your squash should just be fork-tender, and the strands should be slightly firm but pull away easily from the sides.
- Drain off excess liquid from the squash: After you scrape the squash into the bowl, drain off any water that has accumulated at the bottom of the bowl before adding the remaining ingredients.
- Drain the tomatoes well: This will avoid extra liquid being added to the casserole.
- Rinse and drain the beans: Canned beans are packed in liquid that preserve them. Before adding them to your casserole, be sure to rinse them and drain them well to prevent extra saltiness and liquid in the casserole.
- Bake the casserole uncovered: Leave the casserole uncovered as it bakes to help any extra liquid evaporate.
How to Tell When a Spaghetti Squash is Done
The key to a delicious spaghetti squash recipe is cooking it for just the right amount of time. Roasting it too long will make the strands mushy, a mistake many people make. To achieve al dente (tender, with a bite) strands, the cooking time may be less than you think. This varies with the size of the squash, but I recommend starting with 40 minutes at 375 degrees Fahrenheit.
Here are a few ways to check if the spaghetti squash is done:
- It is just tender enough that when you poke it with a fork, it should pierce easily through the skin.
- Flip it over and run a fork through the strands. They should be slightly firm but easily pull away from the sides.
FAQ
It is probably overcooked. To avoid overcooking the squash, follow the suggested cooking time in the recipe card, and don’t let the squash become too soft before taking it out of the oven.
The cooking time varies depending on the size of the squash and the oven. Start checking the squash at 40 minutes and take it out of the oven when it is just tender when you poke it with a fork.
Yes! It is also vegetarian.
Because of the cheese, it is not vegan. You could easily make it vegan by using dairy-free cheese.
You can roast the squash the day before and store it in an airtight container in the refrigerator. Combine all ingredients and bake the casserole when you are ready to eat it.
Storing and Reheating
Store your leftover casserole in an airtight container in the refrigerator for up to three days. Reheat portions by baking or microwaving. Be sure to only reheat the portion you plan on eating, as best practice is to only reheat food once. Always use your best discretion with leftovers.
Other Vegetarian Dinner Recipes
- Zucchini Lasagna
- Baked Taco Casserole
- Vegetarian Chili Recipe
- Vegan Black Bean Soup
- Black Bean Tacos
- Broccoli Pasta
If you try this spaghetti squash recipe or any of my others, please leave a comment telling me what you think. I love hearing from you!
Recipe Video
Spaghetti Squash Casserole
Ingredients
- 1 medium spaghetti squash (2 to 2 1/2 pounds) cut in half with seeds removed, see note
- 3 tablespoons olive oil divided
- 1 teaspoon kosher salt divided
- 1/8 teaspoon black pepper
- 1 small yellow onion diced
- 2 garlic cloves minced
- 1 jalapeño seeds and ribs removed and diced
- 1 teaspoon chili powder
- 1/2 teaspoon smoked paprika
- 1/2 teaspoon ground cumin
- 15 ounces black beans drained and rinsed, see note
- 1 cup frozen corn (no need to thaw it)
- 15 ounces diced fire roasted tomatoes drained very well
- 1 1/2 cups cheddar cheese shredded
Instructions
- Preheat the oven to 375 degrees Fahrenheit. Prepare a rimmed baking sheet with parchment paper and set aside.
- Coat the cut sides of the spaghetti squash with 1 tablespoon of olive oil. Sprinkle with 1/2 teaspoon of kosher salt and a dash of black pepper. Place the cut side down on the parchment-lined baking sheet. Bake the squash for 40 minutes until it is just fork-tender. (Read in the post about how to tell when a spaghetti squash is done.) Remove from the oven and flip to cut side up. Allow to cool for 20 minutes.1 medium spaghetti squash
- While the squash is roasting, heat 2 tablespoons olive oil in a skillet. Add the onion, garlic, and jalapeño. Season with 1/2 teaspoon kosher salt, a dash of pepper, chili powder, smoked paprika, and ground cumin. Cook until the onion is translucent, about 5 minutes.1 small yellow onion, 2 garlic cloves, 1 teaspoon chili powder, 1/2 teaspoon smoked paprika, 1/2 teaspoon ground cumin, 1 jalapeño
- Drain the canned tomatoes very well. I like to do this by placing them in a metal sieve inside of a bowl and allowing them to thoroughly drain while I'm preparing the other ingredients.
- Once cooled, scrape the squash into a large bowl. Drain any liquid that has accumulated in the bottom before moving on to the next step. Add the onion and spice mixture, the black beans, frozen corn, roasted tomatoes, and cheese. Stir to combine.15 ounces black beans, 15 ounces diced fire roasted tomatoes, 1 1/2 cups cheddar cheese, 1 cup frozen corn
- Spray a 9-by-13-inch baking dish with cooking spray. Add the mixture to the baking dish. Bake for 20-25 minutes uncovered. The casserole is done when the edges begin to brown and the cheese is fully melted. Serve with more cheese, pickled jalapeños, and fresh tomatoes.
Notes
Liz says
Can I freeze the spaghetti squash casserole?
Yes, but the texture won’t be quite the same when you reheat it because the squash will release moisture as it thaws.