In a medium bowl, whisk together softened butter, minced garlic, lemon juice, lemon zest, parsley, chives, smoked paprika, onion powder, garlic powder, cayenne, salt, and pepper until smooth. Set half aside for basting and sauce, and use the other half to coat the chicken.

Toss the chicken strips in half of the cowboy butter until fully coated. Let rest at room temperature for 10–15 minutes or refrigerate for up to 2 hours.

Bring a large pot of salted water to a boil. Add linguine and cook according to package instructions until al dente. Drain, reserving ½ cup of pasta water, and set aside.

Heat olive oil in a large skillet over medium-high heat. Add the marinated chicken strips in a single layer and cook without moving until golden, about 3–4 minutes. Flip and cook another 2–3 minutes until cooked through. Transfer chicken to a plate and tent with foil to keep warm.

In the same skillet, add onion and bell peppers. Cook until softened and edges begin to brown, about 4 minutes. Add mushrooms and garlic and sauté until mushrooms release their juices and garlic is fragrant, about 2–3 minutes.

Pour in chicken broth to deglaze the pan, scraping up any browned bits. Stir in heavy cream, Parmesan cheese, and reserved cowboy butter. Bring to a gentle simmer, stirring constantly until the sauce thickens slightly, about 2 minutes. Taste and season with salt and pepper as needed.

Return the cooked chicken to the skillet along with drained linguine. Toss gently to coat everything in the creamy sauce, adding a splash of reserved pasta water if needed.

Sprinkle with extra chopped parsley and extra grating of Parmesan if desired. Serve immediately while hot.