Heat a large pot over medium-high heat. Add the bacon and render until you have enough fat to saute the garlic and onions. Add the garlic and onions and saute until soft, about 5 minutes. Add the pinch red pepper flakes and season with salt and pepper and cook for 1 minute more. Add the greens in handfuls, adding more as the greens start to wilt, tossing with tongs until all the greens are wilted down. Add the chicken stock and cover. Cook until the greens are tender, about 10 minutes.