Season the chicken with salt and pepper on both sides. Heat a large nonstick skillet with 2 tablespoon extra-virgin olive oil, 2 turns of the pan, over medium-high heat. When oil ripples, add chicken and cook 3 minutes on each side then remove and let meat rest and cool. To the same skillet, add another tablespoon extra-virgin olive oil, 1 turn of the pan, and the butter. Melt butter into extra-virgin olive oil and add the shallots and capers. Saute 5 minutes then add chicken stock and reduce 30 seconds. Next, add the juice of 1 lemon and hot sauce and immediately add the spinach - mound up the pan. You will not be able to fit it all in there. Keep turning the spinach and wilting it down until you get it all in there then turn the heat off. Season the spinach with salt and pepper. Serve chicken breasts whole or chopped with spinach mixture.