Step 1: Season your chicken. Pat 1.5 lbs boneless, skinless chicken thighs (or breasts), cut into 1-inch pieces, dry with paper towels. Season generously with 1 teaspoon salt, 0.5 teaspoon black pepper, 1 teaspoon Italian seasoning, and 0.5 teaspoon smoked paprika.
Step 2: Cook the chicken. Heat 1 tablespoon olive oil in a large skillet or Dutch oven over medium-high heat. Add the seasoned chicken in a single layer, ensuring not to overcrowd the pan. Cook for 4-5 minutes per side, until golden brown and cooked through. Remove the chicken from the skillet and set aside on a plate.
Step 3: Sauté aromatics. Reduce the heat to medium. Add 1 tablespoon butter to the skillet, along with 4 cloves garlic, minced, and 1/2 cup drained and chopped oil-packed sun-dried tomatoes. Sauté for 2-3 minutes until the garlic is fragrant and the sun-dried tomatoes are softened.
Step 4: Deglaze and build the sauce. Pour in 1/2 cup chicken broth, scraping up any browned bits from the bottom of the pan. Stir in 1.5 cups heavy cream, 1/2 cup freshly grated Parmesan cheese, 1/4 teaspoon red pepper flakes (optional, for a little kick), and 1/2 teaspoon onion powder. Bring the sauce to a gentle simmer, stirring occasionally.
Step 5: Cook the tortellini. Add 20 ounces fresh cheese tortellini to the simmering sauce. Cook according to package directions, usually 3-5 minutes for fresh tortellini, until al dente and the sauce has thickened slightly.
Step 6: Combine and finish. Return the cooked chicken to the skillet with the tortellini and sauce. Stir in 2 cups fresh spinach, allowing it to wilt into the hot sauce for about 1-2 minutes. Taste and adjust seasoning with additional salt and pepper if needed.
Step 7: Serve. Garnish with extra fresh Parmesan cheese and a sprinkle of fresh parsley, if desired. Serve immediately.