C'mon, doesn't that sound good. We've been a gratin kick around here and we put together a "Gratin Gift Set" for the holidays. It's a Kuhn Rikon peeler set, a Benriner mandoline to slice the potatoes, and a microplane zester for grating the nutmeg. To put things over the top we added a square Le Creuset gratin dish because presentation matters. To finish things off we needed a recipe to go with everything. The classic potato gratin, done well is nothing to sneeze at but we needed something special here so Alex came up with the "onion soup potato gratin" and it is seriously delicious. Instead of using packaged onion soup mix with all of those extra ingredients we simply toasted some onion flakes and infused them in the milk that we used to cook the gratin. Generous amounts of gruyere cheese and touch of nutmeg brought everything together. It's what makes this a perfect gift.
Onion Soup Potato Gratin
85 grams/1/2 cup + 2 teaspoons onion flakes
780 grams/3 cups milk
120 grams/4 ounces heavy cream
2 large eggs
1/4 teaspoons freshly grated nutmeg
6 grams/1 teaspoon salt
4 large russet potatoes, peeled
1/2 large onion
285 grams/10 ounces gruyere cheese, grated
3 quart square gratin dish, lightly buttered
Preheat oven to 350°F
Put the onion flakes on a parchment-lined sheet pan and bake for 6-8 minutes until golden brown. Let them cool down and put them in a medium sized bowl. Pour the milk over the onion flakes, cover and let it infuse in the refrigerator for 4-6 hours.
Preheat oven to 350°F
Strain off the milk, using a spoon to press on the onion flakes and then discard them. Add enough heavy cream to make 2-1/2 cups of liquid. Put the onion milk in a large bowl and whisk in the eggs, nutmeg and salt. Use a mandoline to thinly slice the onions and potatoes directly into the bowl of milk. Mix gently with your hands to blend and coat. Take half the onions and potatoes and spread them evenly in the bottom of the gratin dish. Add half of the cheese in an even layer on top, Add the remaining onions and potatoes, making sure the top is smooth and even. Pour the liquid into the dish. Top with the remaining cheese and cover with foil. Bake for 90 minutes, removing the foil for the last half hour to brown the top. (If you are cooking this in advance, leave the foil on and reheat uncovered for 30 minutes.)
