First, pound out chicken breasts in a partially open ziploc bag. This will help reduce the cooking time and make sure that they cook evenly.
Next, heat some olive oil in a frying pan over medium-high heat. While that is heating, mix 2 tbsp. balsamic vinegar, 2 tsp. dijon mustard and two crushed cloves of garlic in a large bowl. Put the chicken in with the sauce and turn to coat. Cook the chicken in the pan with the sauce about 4 minutes each side. Transfer to a plate when cooked.
We used our Cuisinart food processor with the mandolin attachment to slice ~2 cups of crimini mushrooms.
Then, we heated another bit of olive oil in the same pan and sauteed the mushrooms for about a minute. We added 1/3 cup of chicken broth, thyme and 1 tbsp. balsamic vinegar. Cook, stirring occasionally until the mushrooms are soft, about two minutes longer.
We put the chicken back in the pan with the finished mushrooms to heat the chicken back up.
To serve, top the chicken with the mushrooms. Mmmm…