Repeat process two more times, ending up with cheese on the top
Cover with foil and bake for 50 minutes or until parsnips are fork tender; remove from oven
If you want to add a crispy breadcrumb topping do so now. Melt butter and combine with breadcrumbs; sprinkle over parsnips; if you don't want to add breadcrumbs, go to the next step
2 tablespoons butter (optional), ½ cup breadcrumbs (optional)
Turn oven to broil; remove foil from dish; return parsnips to oven and broil for 3-5 minutes until the cheese (and/or breadcrumbs) are golden brown
Let dish rest for 5 minutes before serving
Notes
Layering the parsnipsIf you want the dish to "look pretty," use the smaller pieces of parsnips on the first two layers; use the biggest slices of parsnips on the top layerCan't find Gruyère?Use a block of Swiss cheese; do not use pre-shredded cheese (it has a anti-coagulating coating on it that doesn't bake well)Heavy creamHeavy cream is often labeled as "whipping cream," or "heavy whipped cream"No leeks?Use shallots or white onionChecking for donenessThe center of a parsnip is pretty tough, so be sure to check a slice of parsnip from the center when testing for donenessServing suggestionLet this cool a few minutes before you serve itI recommend cutting the gratin into square servings versus serving it with a serving spoon (the parsnips aren't as tender as potatoes and if you use a big spoon, it doesn't look as pretty)