Potato Galette with Caraway and Sweet Onions

This delicate galette is made from many, many paper-thin rounds of potatoes.

4 Tbsp. (½ stick) unsalted butter, melted, divided, plus more for pan
½ tsp. caraway seeds
2 Tbsp. rendered duck or bacon fat, melted
1-2 tsp. kosher or sea salt
½ tsp. black pepper, freshly ground
2 lbs medium Yukon Gold potatoes, unpeeled, cut into 1/8' thick slices with a mandolin or V-slicer
1 small sweet onion, such as; Maui, very thinly sliced

Preheat an oven to 425°F (220°C/200°C fan, Gas Mark 7). Arrange a rack in the middle of the oven. Brush a foil- or parchment-lined baking sheet with butter; set springform ring on top.

Toast caraway in a small skillet over medium heat until fragrant, about 1 minute. Let cool. Place in a resealable plastic bag; crush with a rolling pin or bottom of a skillet. Place in a large bowl. Add duck fat, 2 Tbsp. butter, 1 tsp. salt, and pepper. Add potatoes; toss to coat.

Arrange ¼ of potatoes in an even layer inside ring on baking sheet, overlapping as needed. Toss onion in a large bowl with 1 Tbsp. melted butter. Arrange 1/3 of onion over potatoes. Repeat layers twice more, finishing with a layer of potatoes. Carefully remove ring.

Bake until potatoes are tender, about 45 minutes. Brush with 1 Tbsp. butter. Bake until edges of potatoes are deep golden and top is crisp, 5-10 minutes longer.

Run a thin spatula under galette to loosen from foil. Slide onto a platter. Season with salt, if desired.

Makes 6 servings.