Cook pasta according to package directions; drain and set aside.
Slice chicken breasts thin and season with garlic powder, salt, and pepper.
Dredge chicken pieces in flour, shaking off excess.
Heat olive oil and 1 tablespoon butter in a large skillet over medium-high heat.
Sauté chicken until golden brown on both sides and cooked through; remove and set aside.
Add mushrooms to the same pan and cook until tender and golden.
Pour in Marsala wine and let reduce by half, scraping up any browned bits.
Add chicken broth and Dijon mustard; simmer for 2-3 minutes.
Stir in heavy cream and remaining butter; simmer until sauce thickens slightly.
Return chicken to the pan and coat with sauce.
Toss chicken and sauce with cooked pasta.
Serve immediately with Parmesan cheese if desired.