Butternut Mustard (On a Brussel Burger)

Squash Mustard on a Brussel Sprout Burger

I had a bunch of leftovers from my pizzas last week, so I cooked up a tasty burger this past Friday with them. I love having leftover ingredients because sometimes I get extra creative about how to use them, and rather than conceptualizing a dish for a week like I normally do, I just get to improvise. That’s where this awesome squash mustard came from

Some people have been calling me out on the unsightly outlet that is popping up in all my pictures. But did you know that it is code that an outlet needed to be there? Not that I understand building code. But also, its a pretty convenient outlet.

Roasted squash goes into the food processor until smooth. Next I added the mustard seeds that had been cracked and heated up with some vinegar.

Beautiful mustard texture. This was bitter with a little sweet from sugar and the squash. It also had some tang from the vinegar. All in all a tasty mustard that I am excited to try on sandwiches this week!

I fried up the sprouts real quick.

The burger hit the spot and the mustard went perfectly.

The squash flavor isn’t exactly the star of the meal, but in the mustard it adds a nice background sweetness and flavor, and it also gives the mustard a nice body.


Butternut Mustard (On a Brussel Burger)

Homemade butternut squash mustard served on a burger with brussel sprouts.
Prep Time20 minutes
Cook Time6 hours
resting time1 day
Total Time1 day 6 hours 20 minutes
Course: Condiment
Cuisine: American
Keyword: burger, Homemade
Servings: 2 cups of mustard


  • 1 pound diced squash
  • butter salt, pepper, sugar
  • garlic
  • 1/4 cup black mustard seed
  • 1/4 cup yellow mustard seed
  • 1 cup red vinegar
  • pinch allspice
  • pinch cinnamon
  • 1 tablespoon paprika
  • 3 tablespoons sugar


  • about 1 lb diced squash. Roast it at 425 with some butter, salt, and pepper. Throw a garlic clove in there too. Meanwhile, coarse grind ½ cup total black and yellow mustard seeds and add them to a cup of red wine vinegar. Microwave the mustard/vinegar for one minute, then let it sit while the squash roasts.
  • When the squash is tender and starting to brown, about 30 minutes, add it, along with the garlic, to a food processor and blend smooth. Blend in the vinegar mustard mixture and add a pinch of allspice and cinnamon, 1 tablespoon of paprika, 3 tablespoons sugar, and ¼ to ½ cup of water to reach desired texture and mellow out the mixture a bit. Allow to sit overnight before serving.


  1. mmm.. butternut mustard! The mustard seeds look nice against the countertop despite the lovely outlet in the background ;). Nice, creative use of the leftovers! I am now craving a burger.

  2. Awesome idea! Love the cross section especially… that burger is cooked perfectly!
    How did you cook up your burger? pan sear, grill..?
    Super creative! I eat brussels spouts all the time and have yet to convince my boyfriend they are delicious.. especially caramelized and roasted 🙂 Maybe if I use them as a burger topping I will be able to change his mind…

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