01 - Bring a large pot of salted water to a rolling boil. Cook the tortellini according to package instructions until tender. Drain through a colander and set aside.
02 - While the tortellini cooks, heat olive oil and butter in a large skillet over medium-high heat. Add the chicken pieces, season generously with salt, pepper, and dried Italian herbs if using. Sear until golden brown and cooked through, approximately 6 to 8 minutes. Transfer the chicken to a plate and keep warm.
03 - Reduce the skillet heat to medium. Add the chopped onion and cook until softened and translucent, about 3 minutes. Add the minced garlic and sauté until fragrant, roughly 30 seconds, stirring constantly to prevent burning.
04 - Pour in the heavy cream and add the cream cheese and grated Parmesan. Stir continuously and simmer gently until the cheeses are fully melted and the sauce is smooth and velvety, about 2 to 3 minutes.
05 - Add the chopped spinach to the sauce and cook, stirring gently, just until the leaves are wilted and incorporated, about 1 to 2 minutes.
06 - Return the seared chicken and cooked tortellini to the skillet. Toss everything gently until all components are evenly coated in the creamy garlic sauce. Adjust seasoning with additional salt and pepper to taste. Serve immediately, garnished with extra Parmesan and fresh parsley if desired.