Root Vegetable and Whole Grain Mustard Gratin
Breville Test Kitchen

Breville Test Kitchen

Root Vegetable and Whole Grain Mustard Gratin

The veggies are hard…but the slicing is not! The Breville Food Processor effortlessly produces thin, even slices for you to easily toss in the sauce and layer into the dish. A stint in the oven for everything to meld and mingle and your tender creamy cheesy gratin is ready.
the Paradice™ 9
the Paradice™ 9 Product Details

the Paradice™ 9

+3 more appliances


2 hrs total time

20 mins active time


Serves 8-10



  • Comte cheese icon
    5 oz Comte cheese
  • parmesan cheese icon
    3½ oz parmesan cheese
  • clove garlic icon
    4 cloves garlic


  • red onion icon
    1 red onion

    peeled and halved

  • celery root icon
    1⅓ lb celery root

    peeled and cut into large pieces

  • butternut squash icon
    1⅓ lb butternut squash

    peeled and cut into large pieces

  • potato icon
    1⅓ lb potatoes


  • unsalted butter icon
    1 oz unsalted butter
  • yellow mustard seeds icon
    2 tbsp yellow mustard seeds
  • cream icon
    2 cups (16 fl oz) cream


  • thyme leaves icon
    3 tbsp thyme leaves
  • whole grain mustard icon
    2 tbsp whole grain mustard
  • kosher salt icon
    2 tsp kosher salt
  • finely ground white pepper icon
    Finely ground white pepper

    to season


  • 1Assemble the processor with the grey spindle and yellow reversible shredder, with the fine side up in the bowl and shred both cheeses. Remove and set aside.
  • 2Carefully assemble the clean processor bowl with the grey spindle and green S-blade™. Add the garlic and process until finely chopped, scraping down the side occasionally. Carefully remove the S-blade™ leaving the garlic in the bowl.
  • 3Assemble the processor with the grey spindle and orange adjustable slicer set on 2 in the bowl and slice the onion. Remove and set aside.
  • 4With the process still set up with the slicer set on 2, slice the celery root and transfer to a large mixing bowl. Slice the squash and then the potatoes and transfer to the mixing bowl. Mix the vegetables to distribute evenly.
  • 5Melt the butter in a large frying pan over medium-high heat. Add the garlic and onion and mustard seeds and saute for 4 minutes, or until softened. Add 1½ cups (12 fl oz) cream and thyme and bring to a boil. Reduce the heat and simmer for 2 minutes to infuse. Add the whole grain mustard, salt and pepper and stir to combine.
  • 6To preheat the oven, insert the wire rack into position 6. Set the oven to Bake, Convection, 325°F, Rotate Remind, for 1 hour 15 minutes and press Start. Meanwhile, continue to the next step.
  • 7Pour the hot cream over the vegetables. Add the remaining ½ cup (4 fl oz) cream and mix to coat. Place half the vegetables in a 11-inch x 9-inch baking dish and flatten. Sprinkle over half the cheese and repeat with the remaining vegetables and cheese. Cover with foil.
  • 8Once preheated, place in the oven and bake for 1 hour 15 minutes. When the Rotate Remind signals, remove the foil and continue baking until golden brown and the vegetables are tender when tested with the tip of a knife.
  • 9Remove from the oven and allow to stand for 10 minutes before serving. Serve sprinkled with finely chopped parsley, if desired.
Hors d'oeuvr/Appetizers
Gluten Free