Thinly sliced sweet potatoes and russet potatoes baked in a creamy sauce and garnished with sautéed chanterelles and onions.
4 sweet potatoes, peeled
3 russet potatoes, peeled
2 cups heavy cream
Salt and ground white pepper, to taste
Ground nutmeg, to taste
1 med. white onion
1 lb. fresh chanterelle mushrooms
1. Preheat oven to 375ºF. Using a mandoline, thinly slice sweet potatoes, then russets. Place in separate bowls.
2. Cover each bowl of potatoes with 1 cup heavy cream. Season liberally with salt, white pepper, and nutmeg (baking will lessen the intensity of the seasoning).
3. Coat a 9 x 6-in. (standard casserole) pan with butter. Starting at one corner of the pan, place individual slices of sweet potatoes in a row, just overlapping one another.
Move on to the next row, just overlapping the first. Repeat until the pan has a flat layer of sweet potatoes.
4. Top that layer with the russet slices, overlapping in the same orderly manner. Repeat with another layer of sweets, then russets; continue until the pan is full.
5. Pour the remaining cream from the potato bowls over the gratin. Cover with plastic wrap, then aluminum foil (the plastic wrap ensures the potatoes will remain moist and steamy).
6. Bake in the preheated oven for 45-60 min., until the potatoes have absorbed the cream (peel back a corner of the plastic/aluminum wrap to check).
7. Remove the wrap and return the pan to the oven for 10-15 min. more, until the top is a crusty golden brown.
8. While the gratin is browning, caramelize onions in a little butter. Add mushrooms to caramelized onions and sauté until golden.
9. Remove gratin from oven; garnish with sautéed chanterelles and onions.