Bring a large pot of salted water to a boil. Add the 12 oz cheese tortellini and cook according to the package instructions, usually about 3 to 5 minutes for fresh or frozen tortellini. Stir occasionally to prevent sticking. Once tender, drain and set aside, reserving about ½ cup of the pasta water.
While the pasta cooks, heat 2 tablespoons olive oil in a large skillet over medium-high heat. Pat the shrimp dry with paper towels, then season lightly with salt, pepper, and half a teaspoon of Italian seasoning. Add shrimp to the skillet in a single layer and cook for 2 minutes on each side until pink and opaque. Remove shrimp from skillet and set aside.
Reduce heat to medium and add the remaining 1 tablespoon olive oil to the same skillet. Add minced garlic and sauté for about 30 seconds until fragrant but not browned. Pour in 1 cup heavy cream and stir to combine, scraping up any browned bits from the shrimp for extra flavor. Let the cream simmer gently for 2 to 3 minutes until it slightly thickens.
Sprinkle in 1 cup grated Parmesan cheese and the remaining Italian seasoning. Stir continuously until the cheese melts and the sauce is creamy and smooth. Toss in the fresh spinach and cook just until wilted, about 1 minute.
Return the cooked shrimp to the skillet along with the drained tortellini. Gently toss everything together to coat evenly in the creamy garlic sauce. If the sauce feels too thick, add reserved pasta water a tablespoon at a time until you reach your desired consistency.
Taste and adjust seasoning with more salt and pepper if needed. Serve immediately, garnished with chopped fresh parsley for a burst of color and freshness.