- 6 bunches Swiss chard, center ribs and stems removed (about 2 1/2 pounds), or two 10-ounce packages frozen chopped spinach, thawed
- 2 teaspoons kosher salt plus more
- 1/2 cup (1 stick) unsalted butter, divided
- 1 1/4 cups whole-milk ricotta, drained
- 4-5 large egg yolks
- 1 large egg
- 1/4 cup all-purpose flour plus more
- 12 sage leaves, thinly sliced
- Freshly ground black pepper
- Finely grated Parmesan
- Special equipment: Cheesecloth
- If using Swiss chard, fill a large bowl with ice water. Cook chard in a large pot of boiling salted water until tender but still bright green, about 4 minutes. Using tongs, transfer to ice water; let sit until cold.
- Squeeze chard dry. Transfer to a large double layer of cheesecloth; gather ends and squeeze to thoroughly wring out liquid (be sure to use cheesecloth; the chard will stain a kitchen towel).
- Pulse chard in a food processor until minced, about 30 seconds. Return chard to cheesecloth; wring out again to remove any remaining liquid. (If using spinach, squeeze dry with your hands.)
- Transfer chard to a large bowl. Melt 1/4 cup butter in a small saucepan over medium heat. Add melted butter, ricotta, 4 egg yolks, egg, 1/4 cup flour, and 2 teaspoons salt to chard. Using an electric mixer, beat until a dough forms, 1-2 minutes. Alternatively, knead ingredients by hand in a large bowl until mixture holds together when lightly pressed.
- Cook 1 golf ball-size sample portion of dough in boiling salted water for about 5 minutes (to check for texture and seasoning). Taste sample; adjust seasoning if needed. If sample falls apart in the water, mix 1 more egg yolk and 1-2 tablespoons flour into dough until it holds together.
- Lightly flour a rimmed baking sheet. Scoop out scant 2 tablespoons dough; dust with flour and roll between your palms to form an oval-shaped malfatto; place on sheet. Repeat with remaining dough to form 24 malfatti. DO AHEAD: Malfatti can be formed 2 weeks ahead. Freeze on baking sheet, then transfer to a resealable plastic freezer bag. Keep frozen.
- Working in 2 batches, cook malfatti in a large pot of boiling salted water until cooked through, 6-8 minutes per batch (8-10 minutes if frozen). Drain and transfer to a plate; tent with foil to keep warm.
- Meanwhile, heat remaining 1/4 cup butter in a large skillet over medium heat. Add sage and cook until butter foams and begins to turn brown and sage becomes crispy, about 30 seconds. Season sage brown butter with salt and pepper. Divide malfatti among plates; spoon sage brown butter over. Sprinkle with Parmesan.