OSU Casserole–An easy Instant Pot one pot meal of penne pasta, Italian sausage, marinara sauce, peppers, mushrooms, mozzarella and spinach.
OSU Casserole
In the Petersen household we are huge fans of The Ohio State University. Greg grew up near Columbus, Ohio and we love cheering for their awesome football team. (Football starts on Saturday…YAY!!!) This recipe is a nod to OSU.
OSU Casserole also known as Johnny Marzetti started in the 1920s, when Teresa Marzetti was serving this dish to loyal customers at her Italian restaurant in Columbus, Ohio. The restaurant was located near Ohio state university and this dish was a huge hit with the students. By the 1920s the recipe’s popularity spread across the midwest.
My version has a few changes from the original and is made in your Instant Pot in a hurry. This dish has so much flavor thanks to the Italian sausage which flavors the entire dish so nicely. It’s also got lots of vegetables (onions, mushrooms, garlic, peppers and spinach!) so you can use it as a one pot meal. The leftovers freeze nicely for a dinner another day.
Ingredients/Substitution Ideas
- Italian sausage–mild or hot
- Onion–yellow or white
- Mushrooms
- Garlic cloves
- Chicken broth–or beef broth
- Mini penne–or regular penne
- Italian seasoning
- Marinara sauce
- Sugar
- Red or green bell pepper
- Spinach–fresh or frozen
- Mozzarella cheese
Steps
Turn Instant Pot to saute setting. When display says HOT add in the sausage and break it up. Add in the onions. Brown for about 4 minutes. Add in the mushrooms and cook for 2 more minutes. Add in garlic and cook for 30 seconds.
Pour in the broth and scrape bottom of pot so that nothing is sticking. Turn off Instant Pot.
Sprinkle in the penne evenly.
Add in the Italian seasoning, marinara sauce, sugar and peppers. Don’t stir.
Cover Instant Pot and secure the lid. Make sure valve is set to sealing. Set the manual/pressure cook button to 2 minutes. When time is up let pot sit for 5-10 minutes and then move valve to venting. Remove the lid.
Stir in the spinach and half of the mozzarella. Sprinkle the remaining mozzarella on top and let it melt (I used my air fryer lid to melt it).
Serve and enjoy!
Notes/Tips
- Serve with a green salad and garlic bread.
- I used my 6 quart Instant Pot*. You can also make this in an 8 quart pot. Halve the recipe in a 3 quart pot.
- Store leftovers in an airtight container* in the refrigerator for up to 5 days or in the freezer for up to 3 months.
- Other recipes you can make with the other half of the box of penne pasta are Everyday Casserole or Instant Pot Olive Garden Chicken Pasta.
More Instant Pot recipes with penne…
Henny Penny Chicken
Penne pasta and chicken in a creamy white sauce…better than alfredo!
Instant Pot Creamy Turkey Spinach Penne
Saucy penne pasta with ground turkey, tomatoes, green chiles, cumin, cream cheese and spinach. Make it fast in the electric pressure cooker.
Instant Pot Penne in Cajun Mustard Cream Sauce
Make this Instant Pot Penne in Cajun Mustard Cream Sauce for a quick and easy weeknight meal. With options to prepare it with andouille sausage or meatless you can make everyone happy.
Instant Pot Creamy Beef and Penne
Ground beef, garlic, penne pasta, fire roasted tomatoes, cream cheese, spinach and pine nuts cooked quickly and in one pot, your Instant Pot. An amazing pasta dish that your whole family will love!
Did you know you can filter the recipes on my website to search by meat type, IP or Crockpot, low carb, gluten free, etc.? Use the filter to find exactly what you are looking for.
OSU Casserole
- Prep Time: 20 minutes
- Cook Time: 2 minutes (plus 5 minute NPR)
- Total Time: 22 minutes
- Yield: 6–8 servings 1x
Description
An easy Instant Pot one pot meal of penne pasta, Italian sausage, marinara sauce, peppers, mushrooms, mozzarella and spinach.
Ingredients
- 1 lb Italian sausage
- 1 cup diced onion
- 4 ounces sliced mushrooms
- 4 garlic cloves, minced
- 2 cups chicken broth
- 8 ounces mini penne
- 1 Tbsp Italian seasoning
- 1 (24 oz) jar marinara sauce
- 1/4 tsp sugar
- 1/2 of one red or green bell pepper, diced
- 2 cups chopped spinach
- 1 cup shredded mozzarella, divided
Instructions
- Turn Instant Pot to saute setting. When display says HOT add in the sausage and break it up. Add in the onions. Brown for about 4 minutes. Add in the mushrooms and cook for 2 more minutes. Add in garlic and cook for 30 seconds.
- Pour in the broth and scrape bottom of pot so that nothing is sticking. Turn off Instant Pot.
- Sprinkle in the penne evenly. Add in the Italian seasoning, marinara sauce, sugar and peppers. Don’t stir.
- Cover Instant Pot and secure the lid. Make sure valve is set to sealing. Set the manual/pressure cook button to 2 minutes. When time is up let pot sit for 5-10 minutes and then move valve to venting. Remove the lid.
- Stir in the spinach and half of the mozzarella. Sprinkle the remaining mozzarella on top and let it melt (I used my air fryer lid to melt it).
- Serve and enjoy!
- Category: Pasta
- Method: Instant Pot
*Karen Petersen is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.
It was very good as written. Will add parmesan next time.
Thanks Sharon!
even in these trying times i like to try new recipes, but not all of us older people have instant pots as we are on very tight budgets so if you can please do slow cooker methods also it would be appreciated
Another excellent recipe, Karen! I used a package of pre-cooked Butterball Turkey Sausage Crumbles to keep the calories down. I also used whole wheat penne, so the cooking time was increased. We loved it and will enjoy it again! Thanks!
Thanks Kathy!
Made this last night – delicious!
Thanks for the 5 stars Ellen!
I doubled it and used ground beef instead because that’s whale I had in the fridge. Delicious!!
Thanks for the 5 stars! So glad you enjoyed it!
Can I leave out the spinach? My husband has kidney stones and spinach is one of the foods he can’t have.
thank you
I didn’t know there was an “air fryer lid” for the Instant Pot!
I must find this promising accessory, where can I find it?
yep for sure!
Go Bucks!!!
Yes! Love this! Go Bucks!
This looks amazing as all your recipes do. I don’t have an instantpot, though, so how do I make it in the slow cooker?
Pasta has such mixed results in the slow cooker for me so I would adapt to the stove top and oven if you don’t have an instant pot. Here’s how:
1. Cook pasta according to package directions. Strain and set aside.
2. Heat a pan over medium high heat.Add in the sausage and break it up. Add in the onions. Brown for about 4 minutes. Add in the mushrooms and cook for 2 more minutes. Add in garlic and cook for 30 seconds.
3. Add in the penne, Italian seasoning, marinara sauce, sugar, peppers, spinach and half of mozzarella. Stir. Pour into 9×13 inch baking dish.
4. Sprinkle the remaining mozzarella on top and bake at 350 degrees for 15 minutes. Serve and enjoy!
The secret to pasta in a slow cooker is to add it al dente right before you will serve it. Just enough so it’s heated through, Yes, I know it is an extra step but worth it. You can pre-cook your pasta (al dente), drain and add a little olive oil so the sauce will coat it. You can store up to three days in the fridge. I did a Pasta Bar for the church, using the several slow cookers for the different types of pasta. It was a life saver!
Can this recipe be doubled? If so, do I change the timing on the instant pot from 2 to 4 minutes?
you can double it but you would not double the cooking time. Keep the cooking time the same.
This looks delicious. If I want to leave out the pasta, do I need to make any adjustments to the ingredients or cooking process? Thank you!
Yes you’ll need to adjust the recipe. Although I’m not exactly sure. The spaghetti sauce won’t have anything to soak into so it will be just like a big pot of spaghetti sauce with some meat and vegetables…this might not be the right recipe for you if you don’t want the pasta.
Thank you for explaining this to me. I will keep this in mind with all noodle recipes. Again, thank you so very much for sharing your incredible knowledge and experience with these recipes.