1.

Preheat the oven to 400°F. Melt butter in a large skillet over medium heat. Add the leeks. Cook, stirring frequently, until soft and translucent but not browned, about 5 minutes. Add the spinach and chard, and raise the heat to high. Sauté until all the greens are completely wilted and all the liquid has evaporated. Transfer to a bowl to cool.