Prepare Ingredients: Dice the onion into small pieces and mince the garlic. Set them aside. Measure out all ingredients and have them ready for use.
Heat the Skillet: Place a large skillet over medium heat. Add the olive oil and let it heat for about 1 minute. The oil should shimmer but not smoke.
1 tablespoon olive oil
Sauté the Onion and Garlic: Add the diced onion to the skillet. Stir and cook for 3-4 minutes, or until the onion becomes translucent. Add the minced garlic and cook for an additional 1 minute, stirring frequently to prevent burning.
1 small onion, 2 cloves garlic
Cook the Sausage: Add the Italian sausage to the center of the skillet. Break it into small pieces with a wooden spoon or spatula as it cooks. Stir the sausage into the onions and garlic once it’s half-cooked. Continue cooking until the sausage is browned and no pink remains, about 5-6 minutes.
½ pound bulk Italian sausage
Build the Sauce: Stir in the tomato-based pasta sauce, canned diced tomatoes with their juice, chicken broth, and half-and-half. Mix well to combine all the ingredients. Bring the mixture to a boil, stirring occasionally.
2 cups tomato-based pasta sauce, 1 cup canned diced tomatoes with juice, 1 cup chicken broth, ½ cup half-and-half or heavy cream
Add the Tortellini: Once the sauce is boiling, add the frozen cheese tortellini. Stir gently to ensure all the tortellini is submerged in the sauce. Return the mixture to a boil.
12 ounces frozen cheese tortellini
Simmer and Cook: Lower the heat to medium-low and cover the skillet with a lid. Let the tortellini simmer in the sauce for 5-7 minutes, stirring occasionally to prevent sticking. Check that the tortellini is tender by tasting one.
Add Spinach: Remove the skillet from the heat. Add the baby spinach leaves on top of the tortellini and gently stir them in until they are wilted. This should take about 1-2 minutes.
3 cups fresh baby spinach leaves
Adjust Seasoning: Taste the sauce and add freshly ground black pepper if needed. The sausage and Parmesan cheese will add saltiness, so additional salt is typically unnecessary.
½ cup grated Parmesan cheese
Serve and Garnish: Transfer the tortellini to serving plates or a large serving bowl. Sprinkle grated Parmesan cheese over the top. Garnish with freshly chopped basil or parsley, if desired. Serve immediately.
Fresh basil or parsley for garnish