Bring a large pot of salted water to a boil. Cook linguine according to package instructions until al dente. Reserve 1/2 cup pasta water, then drain.

While pasta cooks, toss chicken cubes with garlic powder, onion powder, smoked paprika, cayenne, salt, and pepper.

Heat olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add chicken in a single layer and cook for 3-4 minutes per side until golden and cooked through. Remove chicken from pan and set aside.

Reduce heat to medium. Add the 1/2 cup butter to the skillet. Once melted, add minced garlic and sauté for 30 seconds. Whisk in Dijon mustard, lemon juice, chicken broth, heavy cream, and red pepper flakes. Simmer for 2 minutes.

Stir in Parmesan cheese and parsley. Add the cooked pasta and chicken back to the skillet. Toss to coat, adding reserved pasta water if needed to loosen the sauce. Serve immediately.