Swedish-Style Turkey Meatballs

Mix 2 small onions, coarsely grated, 2 cups panko, and ½ cup whole milk in a large bowl to combine. Add 2 large eggs, 2 lb. ground turkey, ½ tsp. ground allspice, and 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt; season generously with freshly ground pepper. Mix well, then let sit 20 minutes for breadcrumbs to hydrate.

Meanwhile, heat 1 lb. fresh or frozen cranberries, 1 cup orange marmalade (about one 13-oz. jar), lemon juice, and a pinch of kosher salt in a large saucepan over medium-high until bubbling. Continue to cook, stirring occasionally and mashing to burst cranberries, until thickened and jammy, 10–12 minutes longer. Transfer jam to a small bowl (it will thicken more as it cools).

Heat ⅓ cup extra-virgin olive oil in a medium Dutch oven or other heavy pot over medium. Working one at a time, scoop out golf-ball-size portions of meat mixture (it will be sticky, so use a #50 cookie scoop if you have one) and form into 1½"-diameter balls. Working in batches, arrange meatballs in a single layer in pot (about 12 per batch) and cook, turning halfway through with a slotted spoon and adjusting heat as needed if browning too quickly, until deeply browned on 2 sides, about 3 minutes. Transfer to a rimmed baking sheet as you go (meatballs will still be uncooked inside). Pour out any excess fat in pot and discard. Remove any charred bits remaining in pot if needed.

Melt 4 Tbsp. unsalted butter in same pot over medium heat. Add ¼ cup all-purpose flour and cook, whisking constantly, until golden brown, 3–4 minutes. Add 1 Tbsp. balsamic vinegar, 1 Tbsp. Worcestershire sauce, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt and season generously with pepper; whisk to combine (mixture will seize and coagulate). Add 5 cups low-sodium chicken broth, ½ cup at a time, whisking constantly and incorporating completely after each addition before adding more (gravy will thicken and seize at first but smooth out as you go). Bring to a simmer (still over medium) and cook, stirring occasionally, until slightly thickened, 8–10 minutes.

Return meatballs to pot and cook, gently stirring occasionally with a heatproof rubber spatula (this will help to keep the meatballs from falling apart), until gravy thickens even further, 8–10 minutes.

Top meatballs and gravy with chopped parsley; season with more pepper. Serve with mashed potatoes and cranberry jam. Do Ahead: Jam can be made 1 week ahead; cover and chill. Meatballs can be formed 1 day ahead; arrange in a single layer in an airtight container. Cover and chill.