Cut each chicken breast in half lengthwise, place between two sheets of parchment paper and pound until thin. Cut each of those in half again if you prefer smaller pieces of chicken.

Sprinkle both sides of the chicken with salt and pepper and dredge both sides in the flour. Pour 2 Tbsps of the olive oil in a large skillet over medium heat. Add chicken and cook 3-4 minutes per side. Remove chicken from pan and set aside.

Add the other Tbsp of olive oil to the skillet along with the diced onions. Cook the onions 3-4 minutes.

Add the garlic, chicken broth, white wine, lemon juice, capers, and butter. Season with kosher salt and pepper. Bring to a boil, reduce heat to low and simmer for 5 minutes. Remove 1/4 cup of this sauce and set aside.

Bring the heat back up to medium and add the zucchini noodles to the pan, cook for 4-5 minutes, stirring occasionally. Add the chicken back into the pan with the zucchini noodles. Taste for seasoning and add kosher salt and pepper if needed. Serve with reserved sauce over top and more lemon or parsley.