Butterfly both chicken breasts and then tenderize them using the flat size of a meat mallet to make them a uniform 1/4 inch thick. Season both sides of the chicken with salt and pepper.
Heat a large skillet over medium heat. Add the olive oil, heating for 1 minute and then adding the chicken breasts. Sear on both sides until golden brown, approximately 3-4 minutes per side. Remove to a paper towel lined plate.
Without wiping out the skillet, add the shallot and garlic, sauteing for 1 minute.
Deglaze the pan with the white wine (or chicken stock), scraping up the browned bits with a spoon.
Stir in the butter, Dijon mustard, whole grain mustard, fresh thyme and Worcestershire sauce. Simmer for 3-4 minutes. Stir in the cream.
Return the chicken breasts to the skillet, spooning the sauce over top, simmer on low for 5 minutes. Sauce will reduce, but not be super thick.
Serve over couscous, rice or buttered noodles to help soak up the sauce.
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