Begin by laying your chicken breasts flat on a cutting board. Use a large sharp knife to slice sideways through the breast carefully. You want to create two plump cutlets, so keep the knife flat and parallel to the cutting board as you cut through. Repeat this process with the second chicken breast.
Next, mix the olive oil, smashed garlic, mustard, salt, and pepper together in a zip-lock bag or a large non-metallic bowl. This marinade is what makes the chicken juicy and flavorful.
Add the filleted chicken breasts to the marinade, ensuring they are well-coated. Set this aside to marinate. You can let it soak for at least 10 minutes, but if you have the time, allowing it to marinate for up to 24 hours will deepen the flavors.
While the chicken marinates, place a large non-stick pan or cast-iron skillet over medium-high heat. Once it’s hot, add a teaspoon of olive oil to the pan.
Remove the marinated chicken breasts from the marinade and pat them dry with kitchen paper. This step will help achieve a nice golden sear.
Once the pan is hot, lay the chicken breasts in a single layer. Cook for about 3 minutes on each side or until they’re golden brown and cooked through. Remove the fillets from the pan and tent them with foil to keep warm.
In the same skillet, add the fresh vegetables: broccoli florets, frozen peas, and green beans. Throw in the chopped garlic and pour in the chicken broth. Stir everything together.
Cook over medium-low heat until the broth just evaporates and the veggies become tender-crisp. This should take about 5 to 7 minutes.
Now it’s time to return the cooked chicken to the pan. Add any juices that have collected on the plate back into the skillet. This step ensures nothing goes to waste!
Lastly, add the butter to the pan. Allow it to melt, spooning the melted goodness over the chicken and vegetables. Serve hot, garnished with fresh basil, and enjoy!