Heat a large skillet over medium heat and add olive oil and 1 tbs butter. Swirl to coat the pan. Add the mushrooms, and cook, stirring often 10 to 15 minutes.
Stir in the chicken stock and deglaze the pan. Add the remaining 1 tbs butter and melt. Stir the mushrooms back into the skillet and let the liquid thicken, 2 to 3 minutes.