Step 1: Prepare the Cowboy Butter. In a small bowl, combine the softened unsalted butter, minced garlic, chopped fresh parsley, chopped fresh chives, Dijon mustard, smoked paprika, red pepper flakes, onion powder, cayenne pepper (if using), and lemon juice. Mix well until everything is thoroughly combined and creamy. Set aside.
Step 2: Prepare the Chicken. Pat the chicken pieces dry with paper towels. Season lightly with salt and freshly ground black pepper. In a large skillet or Dutch oven, heat 1 tablespoon of olive oil over medium-high heat. Add the chicken pieces and sear for 3-4 minutes per side, until golden brown and cooked through. Remove the chicken from the skillet and set aside.
Step 3: Cook the Tortellini. While the chicken is cooking, bring a large pot of salted water to a boil. Add the fresh tortellini and cook according to package directions, usually 2-4 minutes, until al dente. Reserve about 1/2 cup of the pasta water before draining the tortellini. Drain and set aside.
Step 4: Create the Creamy Sauce. In the same skillet used for the chicken (do not clean it, as the fond adds flavor!), reduce the heat to medium. Add the remaining 1 tablespoon of olive oil. Add about 2-3 tablespoons of the prepared cowboy butter to the skillet and let it melt, scraping up any browned bits from the bottom of the pan.
Step 5: Combine Ingredients. Pour in the heavy cream and chicken broth (or reserved pasta water) into the skillet. Bring to a gentle simmer, stirring constantly. Stir in the grated Parmesan cheese until melted and the sauce thickens slightly. Taste and adjust seasoning with salt and pepper if needed.
Step 6: Finish the Cowboy Butter Garlic Chicken Tortellini. Add the cooked chicken back to the skillet with the sauce. Toss to coat thoroughly. Gently add the drained tortellini to the skillet, tossing everything together until the tortellini is well coated in the creamy, garlicky sauce. If the sauce is too thick, add a splash more reserved pasta water until it reaches your desired consistency.
Step 7: Serve. Serve your Cowboy Butter Garlic Chicken Tortellini immediately, garnished with extra fresh parsley, chives, and a sprinkle of Parmesan cheese, if desired. Enjoy!