Step 1

Heat 2 Tbsp. extra-virgin olive oil in a large skillet over medium-high. Cook 1 large red onion, cut into ½" pieces, stirring occasionally, until softened and translucent, 5–7 minutes; transfer to a medium bowl. Add 4 oz. chilled cream cheese, cut into pieces, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and 1½ tsp. garlic powder to bowl and mix to combine, then mix in 1 large egg and ⅔ cup panko. Add two 10-oz. packages frozen chopped spinach, thawed, squeezed dry, 8 oz. extra-sharp cheddar, coarsely grated, and ⅓ cup chopped pickled cherry or other hot peppers and mix again. Set filling aside.

Step 2

Place a rack in middle of oven; preheat to 375°. Lightly whisk 2 large eggs in a large bowl. Using a wooden spoon or rubber spatula, stir in 1 cup low-sodium chicken broth, 1 cup panko, ¼ cup soy sauce, preferably low-sodium, and 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt. Let sit at least 15 minutes and up to 30 minutes (you want panko to hydrate).

Step 3

Add 2 lb. ground beef (15–20% fat) to bowl with egg mixture and mix until fully incorporated (your hands are most efficient for this; there is no fear of overmixing).

Step 4

Lay a few large pieces of plastic wrap on a slightly damp surface to create about a 15" square. Transfer meat mixture to plastic wrap and pat into a ½"-thick 13x9" rectangle. Scatter spinach filling over meat mixture and pat into an even layer, leaving a ½" border of meat mixture exposed on long sides. Starting from the long side closest to you, roll meat mixture into a log, enclosing filling (just as you would a jelly roll), using plastic wrap to lift and shape log. Using plastic wrap, squeeze ends of log closed to seal. Transfer log to a parchment-lined rimmed baking sheet. Carefully remove and discard plastic wrap. Gently reshape meatloaf as needed.

Step 5

Bake meatloaf until golden brown and an instant-read thermometer inserted into center registers 140°, 30–40 minutes. Brush meatloaf with ¼ cup ketchup; bake until ketchup feels tacky, 10–12 minutes. Brush remaining ¼ cup ketchup on top and bake until surface is tacky and thermometer inserted into the center registers 155°, 8–10 minutes. Let meatloaf cool on baking sheet 15 minutes.

Step 6

Transfer meatloaf to a platter; top with parsley leaves with tender stems. Place drained pickled vegetables in a small bowl and serve alongside.Do ahead: Spinach mixture can be made up to 1 day ahead. Cover and chill.