Prepare the Chicken : Slice each chicken breast in half lengthwise to make four thin cutlets. Sprinkle salt and pepper generously on both sides of the chicken. Gently coat the chicken in flour, shaking off any surplus before cooking.

Sear the Chicken : In a large skillet, warm the olive oil over medium-high heat. Add the chicken and sauté for 4 to 5 minutes per side, until it achieves a golden brown color and is fully cooked. Transfer the chicken to a plate and set it aside.

Sauté the Mushrooms : In the same skillet, allow the butter to melt over medium heat. Add the sliced mushrooms and cook for about 5 minutes, stirring occasionally, until the mushrooms are golden and tender. Add the minced garlic and Italian seasoning, cooking for an additional minute until fragrant.

Make the Sauce : Add the chicken broth to the skillet, using a spatula to scrape up any caramelized bits stuck to the bottom to deglaze the pan. Stir in the lemon juice and Dijon mustard, and let the mixture simmer for a minute. Add the heavy cream, stirring to combine.

Combine and Serve : Return the chicken to the skillet, spooning the creamy mushroom sauce over the top. Let everything cook together for a couple more minutes to warm through. Serve hot, garnished with fresh herbs if desired.