Season chicken thighs liberally with salt and pepper.
Place skillet over medium high heat and add 1 tbsp. of butter and 1 tbsp. oil.
Carefully add chicken thighs to the pan and brown on each side, about five minutes per side until cooked through.
Remove chicken from the pan and place on a plate to the side.
Add remaining butter and sliced mushrooms. Sauté for two minutes.
Add chopped asparagus, herbes de provence and minced garlic. Sauté for an additional five minutes until asparagus is tender, but still firm.
Add flour and stir to coat the vegetables cook for one minute.
Carefully stir in chicken stock. As the roux thickens the stock a sauce will form.
Add chicken back to pan, allow to warm for one to two minutes before serving.
Serve with a squeeze of fresh lemon juice if desired.