The Rarebit as Served at Proper Burger Company in Salt Lake City, Utah, as seen on Diners, Drive-Ins and Dives, Season 29.
Recipe courtesy of Proper Burger Company

Rarebit Sauce

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  • Level: Easy
  • Total: 30 min
  • Active: 30 min
  • Yield: 8 cups



  1. In a large sauce pot, bring the beer and milk to a simmer (180 degrees F).
  2. While you are bringing the milk and beer to a simmer, in a separate sauce pot, melt the butter and bacon fat. Once melted, add the onions and sweat until translucent. Add the flour to make the roux, making sure you stir continually so it gets nice and toasty, but doesn't burn to the bottom of the pot. De-glaze the pan with the mustard, Worcestershire sauce, white wine vinegar and thyme. By this time, the milk and beer should be ready to add to the roux. Add slowly, continually stirring to break up chunks and emulsify the mixture. Bring the mixture up to 185 degrees F and remove from the heat. Add the Irish Cheddar, blue cheese and salt and blend with an immersion blender (if you don't have an immersion blender, add the cheese while the mixture is still hot and whisk vigorously with a whisk to fully incorporate).

Cook’s Note

Rarebit sauce is traditionally served on a thick slice of toast. Spread the rarebit on the toast and put it under the salamander or broiler until the sauce is hot and bubbly. Serve as toast, or as an open-faced sandwich with bacon, red onion, and tomato. To use on top of a burger, heat the rarebit sauce and ladle over the burger patty and any accompanying ingredients. To use as a cheese sauce for fries, heat and ladle over fries. We recommend adding diced tomato, minced red onion, and bacon lardons.