01 - Bring a large pot of salted water to a boil. Cook pasta according to package directions until al dente. Drain, reserving 1/2 cup of pasta water, and set aside.
02 - Heat 1 tablespoon butter in a large skillet over medium-high heat. Season chicken pieces with salt and pepper, add to the skillet, and sauté until golden and cooked through, approximately 5-6 minutes. Transfer to a plate and set aside.
03 - In the same skillet, add red and yellow bell peppers with red onion. Cook for 3-4 minutes until softened. Add garlic and continue cooking for 1 minute until fragrant.
04 - Reduce heat to medium. Add remaining butter, Dijon mustard, lemon juice, Worcestershire sauce, hot sauce, smoked paprika, red pepper flakes, oregano, parsley, and chives. Stir continuously until butter melts and mixture becomes aromatic.
05 - Pour in heavy cream and sprinkle Parmesan cheese into the skillet. Stir constantly until sauce achieves a smooth, creamy consistency and cheese is fully incorporated.
06 - Return cooked chicken to the skillet along with baby spinach. Cook for approximately 1 minute until spinach just begins to wilt.
07 - Add drained pasta to the skillet, tossing thoroughly to coat all pieces in sauce. If consistency is too thick, gradually add reserved pasta water until desired creaminess is achieved.
08 - Taste the dish and adjust seasoning with additional salt, pepper, or lemon juice as needed. Serve immediately while hot, optionally garnished with extra fresh herbs and Parmesan cheese.