Crispy Gnocchi With Littleneck Clams

Preheat to 425°F. Prick potatoes all over with a fork and place directly on oven rack; roast until flesh is very soft when squeezed gently and skin is crisp, 60–75 minutes. Immediately slice open lengthwise and scoop out flesh; set skins aside. Pass potato flesh through ricer onto a clean work surface. Let cool.

Meanwhile, bring clams, reserved potato skins, and 1 cup water to a boil in a large pot. Cover and cook, shaking pot occasionally, until clams open, 5–8 minutes; discard any clams that do not open. Pluck clams from shells and place in a medium bowl. Cover and chill until ready to use. Pour clam cooking liquid through a fine-mesh sieve into a small bowl. Cover and chill until ready to use.

Dust riced potatoes with 3/4 cup flour and sprinkle with 2 tsp. or 1 1/2 tsp. salt. Drizzle egg over, then use a fork or your fingers to gently mix ingredients until just incorporated and a smooth dough forms (be careful not to overwork or cooked gnocchi will be gluey and tough), about 3 minutes. Transfer dough to a pastry bag fitted with 1/2" round tip. (Alternatively, use a large resealable plastic bag and snip off 1 corner.)