This gratin tastes great with a salad. You can also serve a square of it in the middle of a bowl of squash and carrot soup topped with yogurt and chives. This gratin is delicious but don't be put off by the color. It can turn a bit greenish purple because of the pesto. I undercooked this twice. Carefully test the center to make sure all the potatoes are tender. Undercooked potatoes are such a bummer.

1 cup parmesan cheese, grated

1 cup percorino, grated

4 shallots, peeled and sliced into thin rings

1 tablespoon balsamic vinegar

6-8 medium-sized yukon gold potatoes (don't use Idaho for this recipe)



1 1/2 cups broccoli, kale, walnut pesto

Preheat oven to 375º F. Butter 1 large casserole dish (about 8x12) or 6 small ones. Combine the grated cheeses. Place shallots in a bowl and pour over the balsamic. Set aside.

Peel the potatoes and place them in cold water. Warm the pesto in a double boiler if it's not freshly made (to loosen it up). Thinly slice (paper thin) the potatoes with a mandoline, a cuisinart slicer attachment, or by hand. Place half the slices into the pesto and gently mix by hand to coat the slices. Spread one layer of sliced potatoes without the pesto down in the dish, overlapping them. Sprinkle with cheeses, salt, and pepper. Spread out and overlap a layer of potatoes covered with the pesto. Place down another layer of potatoes without the pesto. Sprinkle again with cheeses, salt, and pepper. Alternate pesto, no pesto, pesto, and so on until you reach the top of the dish. Just know that the gratin will sink down a bit so do as many layers as you can and press them down a bit. Make sure the final layer doesn't have pesto. Top the gratin with with the remaining cheeses. Grate more on top if you need to. Scatter balsamic shallots over the top. Bake until the potatoes are tender and the top is golden brown (at least 1 hour and 15 minutes, maybe longer). Turn the oven down or cover the gratin if the top starts to burn. Serve immediately.