Step 1

Preheat oven to 400 degrees F (205 degrees C).

Step 2

Pour olive oil in an 8x8-inch glass baking dish. Place the chicken breasts in the dish, coating each side with oil. Squeeze the juice of 1/2 lemon over each chicken breast. Slice the rest of the lemon and place a lemon slice on top of each chicken piece.

Step 3

Bake in the preheated oven until no longer pink in the center and the juices run clear, 30 to 40 minutes. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).

Step 4

Melt butter in a skillet over medium heat; add mushrooms. Cook and stir until mushrooms are brown and liquid is evaporated, about 6 minutes. Sprinkle flour over mushrooms and stir until coated. Add chicken broth, stirring to make a medium-thick sauce. Allow sauce to reduce, adjusting with a little more broth to make a creamy sauce. Add fresh parsley at the last minute. Spoon the sauce over the baked chicken breasts.