Cook the tortellini according to the package directions. Drain and set aside.
Heat the olive oil in a large skillet over medium heat. Add the garlic and sun-dried tomatoes. Cook for 1-2 minutes, stirring frequently until fragrant.
Stir in the fat-free half & half, chicken broth, and Italian seasoning. Bring to a gentle simmer, then stir in the Parmesan cheese. Cook for 3-5 minutes, stirring until the sauce begins to thicken. Avoid boiling vigorously.
Stir in the baby spinach and cook until wilted, about 1-2 minutes. If the sauce needs thickening, stir in the cornstarch slurry and simmer briefly.
Add the cooked tortellini to the skillet and gently toss to coat. Season with salt and black pepper to taste. Serve immediately.