Season chicken fillets with salt, pepper, paprika, onion powder, and thyme. Dredge in flour to coat evenly.
Heat olive oil and 1 tablespoon butter in a large pan over medium-high heat. Cook chicken fillets 5-6 minutes, turning once, until lightly golden and cooked through.
Transfer chicken to a plate and let rest.
In the same pan, melt remaining 1 tablespoon butter. Add minced garlic and sauté for 30 seconds, stirring constantly.
Pour in chicken stock and simmer 1-2 minutes until reduced by half.
Add heavy cream and Dijon mustard, reduce heat to medium, and cook 2 minutes until slightly thickened.
Stir in Parmesan cheese, season sauce with salt and pepper, then return chicken fillets to the pan. Simmer 2-3 minutes to heat through.
Serve chicken with mashed potatoes, rice, or pasta, steamed greens, garnished with parsley and a lemon squeeze.