01 - Pat the chicken thighs dry with paper towels. Season both sides generously with salt, black pepper, and smoked paprika, pressing the spices into the meat to adhere.
02 - Heat olive oil in a large skillet over medium-high heat until shimmering. Add chicken thighs, top side down, and sear for 5-6 minutes until deep golden brown. Flip and cook 3-4 minutes longer. Transfer to a plate and set aside.
03 - Reduce heat to medium. Add mushrooms and onion to the skillet, stirring occasionally for 4-5 minutes until softened and lightly browned. Add minced garlic and cook 1 minute until fragrant, being careful not to burn.
04 - Pour in chicken broth, using a wooden spoon to scrape up any browned bits from the bottom. Stir in heavy cream, Dijon mustard, and thyme. Bring the mixture to a gentle simmer.
05 - Return chicken thighs to the skillet along with any accumulated juices. Simmer uncovered for 15-18 minutes, turning once halfway through, until chicken is cooked through (165°F internal temperature) and sauce has thickened slightly.
06 - Stir in grated Parmesan cheese until melted and fully incorporated. Taste and adjust seasoning with additional salt and pepper if needed. Sprinkle with fresh parsley and serve hot.