Cook the Pasta
Bring a large pot of well-salted water to a boil. Cook linguine until al dente. Reserve ½ cup pasta water, then drain.
Cook the Chicken
Season chicken with paprika, garlic powder, salt, and pepper. Heat olive oil in a large skillet over medium-high heat. Cook chicken until golden and cooked through. Remove and set aside.
Make the Cowboy Butter Sauce
Lower heat to medium. Add butter to the skillet and let melt. Stir in garlic and cook until fragrant (about 30 seconds). Add Dijon mustard and red pepper flakes.
Brighten the Sauce
Remove from heat and stir in lemon juice and fresh herbs.
Combine
Add cooked linguine and chicken back to the skillet. Toss to coat evenly, adding pasta water as needed for a silky sauce.
Serve
Taste and adjust seasoning. Serve immediately.