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Casserole of rainbow chard and leek gratin, with spoon out

Thanksgiving Must-Have: Creamy Leek and Rainbow Chard Gratin

  • Author: Katy Keck
  • Total Time: 1 hour 45 minutes
  • Yield: Serves 6 - 8 1x


This rainbow chard gratin is inspired by my Aunt Mary’s spinach casserole. She was quite colorful and deserves the rainbow. Packed with flavor from caramelized leeks and some nutty Gruyere, with a touch of the creamy goodness of sour cream, this will be the newest must-have on your Thanksgiving menu.


  • 2 pounds of rainbow chard (approximately 23 bunches)
  • 4 Tablespoons of butter, divided
  • 1 teaspoon sea salt
  • 1 teaspoon red pepper flakes
  • 2 leeks, split lengthwise, cleaned and thinly sliced
  • 2 cups sour cream
  • 4 ounces Gruyere, grated
  • 1 cup grated Parmesan
  • 4 pieces of bacon, cooked and coarsely crumbled


Prepare the chard: Place the chard leaves in the sink or a large bowl and fill with cool water. Let them soak, then lift from the sink, rinsing, leaving any grit at the bottom of the sink or bowl. Dry on towels or spin, in batches, in a salad spinner. 

Separate the stems and leaves: Trim the root end of each stem, then cut a “V” in each leaf to remove the full stem. Cut the stems into 1/2″ wide pieces and set aside. Stack the leaves and roll tightly into a long tube shape, then cut cross-wise into 1/4 – 1/2″ pieces. 

Cook the chard: Melt 2 Tablespoons of butter in a large sauté pan. Add the stems and cook, stirring occasionally, for 10 – 12 minutes, until softened and lightly browned. Transfer to a large bowl. 

Add half the leaves and a drop (1 – 2 teaspoons) of water. Cover and cook until wilted, about 4 -5 minutes. Remove the lid and let any accumulated water cook off. Transfer to the bowl with the stems. Repeat with the remaining leaves. 

Return the first batch of leaves and the stems to the sauté pan and stir to combine, cooking off any excess moisture. Season with salt and pepper. Return to the mixing bowl.

Cook the leeks: Melt the remaining 2 Tablespoons of butter in the sauté pan and add the leeks. Cook over high heat for 10 minutes, or until lightly browned, stirring occasionally and scraping up any brown bits from the pan. Add to the bowl with the chard. 

Mix: Add the sour cream and Gruyere to the bowl and stir to combine. Adjust seasoning as needed. 

Finish the chard gratin (bake now or refrigerate for up to 24 hours): Transfer the mixture to a buttered 8 x 12″ or 3 quart casserole. Top with the grated Parmesan and crumbled bacon. At this point, you can cover and refrigerate for up to one day. (Thanksgiving prep for the win!)

Bake in a pre-heated 350oF oven for 30 – 40 minutes, or until the top is golden brown and bubbly.


This is a great make-ahead dish, especially since it takes a bit of time to clean and cut the chard. You can get the majority of the prep done a day ahead and then bake it off when ready to serve. If it’s Thanksgiving and the oven is very busy, you can bake this off while the turkey is resting and being carved. 

Aunt Mary approves!

Creamed spinach and artichoke hearts: If you find yourself short on time, you have my permission to go for the original which is really quick to make. Sauté one chopped onion in 2 Tablespoons of butter. Transfer to a mixing bowl and add two boxes of frozen spinach (thawed and well-squeezed) and one box frozen artichoke hearts, thawed. Stir in one pint of sour cream and add salt and pepper to taste. Spread into a buttered 8 x 8″ baking dish (or similar sized soufflé dish) and sprinkle 1 cup Parmesan on top. Bake in a preheated 350oF oven for 30 – 40 minutes. Serves 8. 

  • Prep Time: 30 minutes
  • Cook Time: 1 hour 15 minutes
  • Category: Side
  • Method: Stovetop + Oven
  • Cuisine: French

Keywords: chard gratin, leeks