Mustard Gratin with Potatoes & Parsnips


Preparation info

  • Difficulty


  • Serves

    6 to 8

Appears in

Home Made Christmas

Home Made Christmas

By Yvette van Boven

Published 2018

  • About


  • Sea salt
  • 1⅔ pounds (750 g) waxy potatoes, cut into ½-inch (1.5-cm) cubes
  • 1⅔ pounds (750 g) parsnips, cut into ½-inch (1.5-cm) cubes
  • 5 tablespoons (75 g) butter
  • ½ cup plus 2 tablespoons (75 g) all-purpose flour
  • About cups (600 ml) milk
  • 2 tablespoons coarse mustard
  • 2 tablespoons white wine vinegar
  • 2 teaspoons fresh thyme leaves
  • freshly ground black pepper
  • A handful of breadcrumbs
  • About ¼ cup (25 g) grated Parmesan cheese



Bring a large saucepan of salted water to a boil. Add the potatoes and pars-nips and cook for about 12 minutes, until they are al dente. Drain in a sieve and let the liquid evaporate. Slide them into a baking dish.

Melt the butter in a saucepan, stir in the flour, and cook for about 3 minutes. Stir in the milk and keep stirring—with a whisk—until you have a smooth sauce. Don’t worry if your sauce has lumps at first, keep stirring: It will smooth out.

While stirring, allow the sauce to reduce until it has the consistency of thin yogurt. Season with the mustard, vinegar, thyme, salt and pepper. Pour the sauce over the vegetable cubes in the baking dish.

Mix the breadcrumbs with the cheese and some pepper. Sprinkle the entire dish with it. You can do all of this in advance.


Preheat the oven to 350°F (180°C).

Bake the gratin for about 35 minutes, until the top is a nice golden brown and the sauce bubbles beautifully.