Olive Oil Galette With Spicy Greens

Heat oil in a large skillet over medium. Add leek and cook, stirring, until softened and wilted (don’t let it take on any color), 6–8 minutes. Add garlic and red pepper flakes and cook, stirring, just until garlic begins to soften, about 1 minute. Add Swiss chard by the handful, letting each addition wilt slightly before adding more; cook, stirring often, just until chard is tender, about 4 minutes. Remove from heat; season with salt and pepper. Transfer Swiss chard mixture to a large bowl and let cool 20 minutes. Mix Parmesan into filling.