Heat 1 tablespoon olive oil in an extra-large skillet or large pot over medium-high heat.
Add the minced garlic and sauté about 30 seconds until fragrant.
Add the turkey sausage, breaking it up with a spoon, and cook until no longer pink, stirring occasionally.
Stir in the marinara sauce, diced tomatoes, chicken broth, and 1/2 cup water; bring the mixture to a gentle boil.
Add the tortellini, toss to combine and press the pasta down into the sauce, then reduce heat to medium-low, cover, and simmer about 10 minutes, stirring once halfway through, until tortellini are cooked.
Stir in the chopped spinach and parsley; season with freshly ground black pepper to taste (add salt only if needed) and toss gently until the spinach wilts.
Stir in the chopped basil and serve warm.