Heat olive oil in a large 12-inch skillet over medium heat for about 1 minute until it shimmers. Pat chicken pieces dry with paper towels, then season them generously with salt and pepper. Add chicken to the hot pan in a single layer without overcrowding. Saute for 5-7 minutes, flipping occasionally, until the chicken turns golden brown on all sides and reaches an internal temperature of 165°F.

Add minced garlic to the skillet with the cooked chicken and stir constantly for about 1 minute until fragrant. Watch it closely because garlic can turn from perfect to burnt in seconds.

While the chicken cooks in Step 1, bring a separate pot of salted water to a rolling boil. Add tortellini and cook according to package directions until al dente, usually 3-4 minutes for fresh tortellini. Drain the pasta but save about 1/2 cup of the starchy pasta water before draining.

Lower the heat under your skillet to medium-low and pour in the heavy cream and Italian seasoning. Stir everything together and let it simmer gently for 3-4 minutes until the sauce thickens enough to coat the back of a spoon.

Add the drained tortellini, fresh spinach, and Parmesan cheese to the skillet. Toss everything together gently for about 1-2 minutes until the spinach just begins to wilt and the cheese melts completely into the sauce. If the sauce seems too thick, add reserved pasta water one tablespoon at a time until you reach your desired creamy consistency.

Taste and adjust seasoning with additional salt and pepper as needed. Serve immediately with extra Parmesan cheese if desired.