Pat chicken thighs dry with paper towels. Season both sides evenly with kosher salt, black pepper, garlic powder, and paprika.
Heat olive oil and 1 tablespoon of butter in a large cast-iron skillet over medium-high heat. Add chicken thighs and sear for 5-6 minutes undisturbed until deeply golden brown. Flip and sear for 4-5 minutes on the second side. Transfer chicken to a plate.
Reduce heat to medium. Melt the remaining 2 tablespoons of butter in the skillet. Add minced garlic, chopped rosemary, and fresh thyme, stirring constantly for 60 seconds until fragrant.
Pour in the chicken bone broth, using a wooden spoon to scrape up all browned bits from the bottom of the skillet.
Pour in heavy cream and bring to a gentle simmer for 3 minutes until slightly thickened. Stir in grated parmesan cheese until melted and smooth.
Return chicken thighs and any resting juices back to the skillet. Simmer for 3-4 minutes until chicken reaches 165°F (74°C) internally and sauce coats the back of a spoon.
Spoon warm garlic herb cream sauce over chicken thighs, garnish with fresh herbs, and serve immediately with mashed potatoes or warm crusty bread.