Rosemary Chicken with Portabella Mushrooms

3 large boneless skinless chicken breasts
4 tbs butter, divided
1 tbs olive oil
10 oz package baby portabella mushrooms
1 clove garlic, minced
½ cup rich chicken stock
1 tsp crushed rosemary (or 1 large bruised sprig fresh)
1 cup heavy cream
Seasoned Flour:
1 cup flour
2 tsp salt
1 tsp pepper
2 tsp garlic powder

lice each breast into 2 pieces, as if you were going to butterly it, except cut all the way through.
Mix the seasoned flour ingredients together in a plastic storage bag. Pound each piece down with a meat mallet to a uniform thickness between 2 sheets of waxed paper. 
Slice each mushroom in half; set aside.

Heat 2 tbs of butter and the 1 tbs of olive oil in a large skillet over medium high heat.

Add about 3 breast portions to the bag of seasoned flour and shake to coat. Place in skillet and brown well on both sides. Depending on how large your pan is, you may have to do this in shifts. Remove browned chicken from the pan and set aside.

Add the remaining 2 tbs of butter to the skillet. Add the mushrooms and garlic, sauteeing over medium heat for about 5 minutes.

Add the ½ cup of stock and the rosemary and deglaze the pan.

Add the browned chicken back to the pan, cover, reduce heat and cook for 20 minutes.

Remove chicken and mushrooms from pan. Add the cream and heat through over medium-low heat until the sauce is reduced by 25%. This should only take about 5 minutes after it begins to bubble.

Add chicken and mushrooms back to pan and heat through. Spoon sauce over chicken and mushrooms to coat.