Preheat the oven to 350°F (175°C).
Sprinkle both sides of the chicken thighs with garlic powder, salt, and pepper.
In a large skillet over medium-high heat, melt 2 tbsp of butter (add olive oil if desired). Add the chicken and sear for 4–5 minutes on each side until golden brown. Remove from skillet and set aside.
Add lemon juice and the remaining 2 tbsp of butter. Whisk and scrape the bottom of the pan to loosen browned bits.
Stir in minced garlic and cook for 30 seconds. Pour in chicken broth and whisk, then add heavy cream. Season with salt and pepper to taste.
Return the chicken to the skillet. Cover with aluminum foil and bake for 30 minutes, or until the internal temperature reaches 165°F.
Spoon the creamy lemon garlic sauce over the chicken. Serve over pasta, rice, or mashed potatoes, and garnish with lemon zest or fresh herbs if desired.