Heat the olive oil in a large skillet over medium heat. Add the onion and garlic, season with salt and black pepper, and sauté for 2-3 minutes, until they begin to soften and become fragrant.
Add the Italian sausage, breaking it into small pieces with a wooden spoon. Cook for 4-5 minutes, until browned and mostly cooked through.
Add the cherry tomatoes, marinara sauce, and beef broth to the skillet and stir to combine.
Increase the heat to medium-high and bring the mixture to a boil. Add the frozen tortellini and cover the skillet. Reduce the heat to medium and cook according to the lowest al dente cooking time on the package, usually 6-8 minutes.
Remove the lid and stir in the baby spinach and heavy cream. Cook for 1-2 minutes, just until the spinach has wilted.
Remove the skillet from the heat. Taste and adjust the salt and black pepper as needed, remembering that the Parmesan will add extra saltiness.
Stir in the freshly grated Parmesan and chopped basil until combined.
Garnish with additional fresh basil, if desired. Serve immediately with a garden salad and breadsticks, and enjoy!
Notes
Tips
Keep the tortellini frozen until you're ready to add it directly to the skillet.
Check the cooking instructions on your tortellini and use the shortest recommended al dente cooking time to avoid overcooking it.
For a quick way to halve cherry tomatoes, place them between two flat plastic container lids, press gently on the top lid, and carefully slice horizontally between the lids with a serrated knife.
Wait to add the Parmesan before making any final salt adjustments, as the cheese adds plenty of savory, salty flavor.
Substitutions
UK readers: Italian sausage isn't as widely available in UK supermarkets as it is in the US. Use good-quality pork sausages instead—simply remove and discard the casings, then crumble the sausage meat into the pan. For a flavor closer to Italian sausage, choose sausages seasoned with herbs or fennel.
Marinara sauce is essentially a tomato-based pasta sauce. UK readers can use a good-quality tomato and herb pasta sauce if marinara isn't available.
In the UK, heavy cream is sold as double cream.
You can use fresh refrigerated tortellini instead of frozen, but adjust the cooking time according to the package instructions.
Leftovers
Let leftovers cool before transferring them to an airtight container and refrigerating.
The tortellini will continue to absorb some of the sauce during storage, so you may need to add a splash of broth or water when reheating.
Reheat thoroughly until piping hot throughout before serving.
Freezing the finished dish isn't recommended, as the cooked tortellini and creamy sauce may change in texture after thawing.