Season the chicken thighs with salt, pepper, thyme, and rosemary.
In a large skillet, melt butter over medium heat.
Add the chicken thighs skin-side down and sear until golden brown, about 5-7 minutes.
Flip the chicken and cook for an additional 5 minutes.
Remove chicken and set aside.
Add diced onions and garlic to the skillet, sauté until translucent.
Sprinkle flour over the mixture and stir to combine.
Gradually whisk in chicken broth, ensuring no lumps remain.
Add the chicken back to the skillet and bring to a simmer.
Cover and cook for 25-30 minutes until chicken is cooked through.
Stir in heavy cream and adjust seasoning if needed.