Prepare the chicken breasts by cutting them in half horizontally to create two thinner pieces. Pat them dry with a paper towel to remove excess moisture.
Season both sides of the chicken breasts with kosher salt and freshly cracked black pepper. Ensure even distribution by seasoning from a height.
Heat a stainless steel sauté pan over high heat and add vegetable oil. Once the oil is shimmering and slightly smoking, place the chicken breasts in the pan, laying them away from you to avoid splashes.
Cook the chicken breasts without moving them until they are golden brown on one side. Flip them over and continue cooking until they reach an internal temperature of 150-155°F. Remove from the pan and let them rest on a rack.
In the same pan, add a little fresh oil and sauté the diced shallots until they are soft. Add the garlic and cook until both are caramelized.
Pour in the chicken stock to deglaze the pan, scraping up the fond from the bottom. Reduce the stock by half over medium-high heat.
Add butter to the reduced stock, stirring to emulsify and thicken the sauce. Season with a pinch of salt and pepper, and finish with a squeeze of fresh lemon juice.
Stir in chopped parsley for a fresh flavor. Serve the chicken breasts sliced on a plate with the pan sauce drizzled underneath to maintain the crispy texture.