Root Vegetables au Gratin

These Root Vegetables au Gratin give you lots of side veggies in 1 dish!

What a great way to get a few vegetables in your menu all in one dish! This one has beets, sweet potato, Yukon Gold potatoes, onion all bathed in a sherry béchamel sauce, topped with nutty cheese and panko!

The sherry béchamel takes this up a notch flavour-wise!

Choose a cheese you like but a softer cheese that melts nicely and has a bit of nuttiness is a good choice. Swiss, Jarlsberg or Gruyère tend to be my favourites but Havarti or Mozzarella would work too.


I served this as part of my Thanksgiving menu but it doesn’t need to wait for a special occasion!

There is a bit of slicing involved but nothing too onerous. And what you spend in slicing you save on pots and pans!

I served it beside these Cornish Hens With Orange Apricot Glaze and it worked really well.

Table setting Cornish hens, stuffed with Root Vegetable casserole and baked squash.

This recipe serves 6 generously. It reheats nicely as well in case you have leftovers.

Chef’s Tips for Root Vegetables au Gratin

  • Slice the vegetables about 1/8-1/4″ thick and as uniform as possible. The thicker the slices the longer the cook time.
  • When you are  making the béchamel sauce you must whisk it constantly to avoid lumps.  Other than that it is pretty straight forward.  If you don’t have Sherry on hand you can skip it or substitute white wine or dry vermouth.
  • Don’t skip the part about covering the casserole with foil for pat of the cooking. This has a long cook time so you don’t want the cheese to overcook and brown and you don’t want your crumb topping too dark either.
Casserole of layered root vegetables with bechamel, cheese and panko topping.

Root Vegetables au Gratin

All your veggie sides in one dish!
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Course: Sides
Cuisine: American
Prep Time: 30 mins
Cook Time: 1 hr 20 mins
Total Time: 1 hr 30 mins
Servings: 6 people


Bechamel Sauce

  • 2 Tbsps butter
  • 2 Tbsps flour
  • 1/2 tsp salt
  • 1/2 tsp pepper
  • 1/4 cuup dry sherry
  • 2 cups whole milk or cream
  • 1/4 tsp nutmeg

Root Vegetables

  • 2 large Yukon Gold potatoes
  • 1 large sweet potato
  • 1 large beet
  • 1 large yellow onion
  • 1 Tbsp flour


  • 2 1/4 cups grated cheese like Havarti and/or Gruyère You can also sub in Swiss or Jarlsberg


  • 8 Tbsps butter
  • 2 cup Panko bread crumbs
  • ½ tsp salt
  • ½ tsp pepper


  • Preheat oven to 350°F. Butter a 9 X 11 inch casserole dish.


  • Melt butter over medium low heat in a medium saucepan. Whisk in the flour, whisking constantly for about 1 minute. Add salt and pepper.
  • Add sherry, whisking constantly for about 1 minute. Raise heat to medium. Whisk in the cream, whisking constantly until mixture beings to bubble and thicken. Add nutmeg. Remove from heat when mixture is the thickness of a cheese sauce. Set aside.

Vegetables & Cheese

  • Peel the potatoes, beet and onion. Cut them in half vertically and then slice thinly cross-wise. Shoot for slices to be of similar width. A mandolin on thick slice setting would work well here. Sprinkle the flour over the onion slices to coat.
  • Layer the vegetables in the buttered casserole dish starting with a layer of beet slices, then half the onion. Spread 2/3 cup of Béchamel over the slices. Then layer Yukon, sweet potato and then the remaining onion. Top with remaining béchamel sauce.
  • Distribute grated cheese evenly over the casserole.
  • Spray a sheet of foil with baking spray and loosely tent the casserole dish. Bake for 40 minutes covered. Do not pinch down the sides. You do not want the vegetables to steam.
  • While casserole is baking melt the butter for the topping. Add the salt and pepper. Toss in the panko crumbs and toss to coat.
  • Remove casserole from oven after the 40 minutes above. Distribute crumbs evenly over the top and return to the oven for another 20 minutes uncovered. Check if a fork can easily pierce the vegetables. Return to oven if needed. If crumbs are getting too dark lay the sheet of foil loosely over the top of the casserole again.
  • Remove from oven when vegetables are fork tender.


Note:  Cooking time will depend on the actual size of your casserole and the thickness of your slices.  Mine actually took one hour and 20 minutes to become fork tender.  Don’t skip the foil or your cheese and crumb topping may get too dark.


Calories: 559kcal | Carbohydrates: 50g | Protein: 23g | Fat: 31g | Saturated Fat: 18g | Cholesterol: 93mg | Sodium: 738mg | Potassium: 1030mg | Fiber: 6g | Sugar: 12g | Vitamin A: 9269IU | Vitamin C: 24mg | Calcium: 673mg | Iron: 2mg
Root Vegetables au Gratin

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