Cut the root and dark green tops off of the leeks. Cut in half lengthwise and wash between the layers to remove any dirt.
Place leeks cut side down in an oven-safe pan with ½ cup water. Cover and simmer on the stove top on low for about 5 minutes or until slightly tender, drain.
Place leeks back in the oven-pan cut side down and sprinkle with salt, pepper and chili flakes. Drizzle with ½ of the butter and bake for 15 minutes
Remove leeks from the oven and flip over. Season with additional salt, pepper and chili flakes. Drizzle with remaining butter and top with Parmesan cheese and bake for an additional 10-15 minutes, or until a fork is easily inserted.