Meatball Calzones with Broccoli and Provolone

Heat broiler. Line a rimmed baking sheet with nonstick foil. Line a second baking sheet with parchment. In a large bowl, whisk together the egg, 2 tablespoons water and 1/2 teaspoon each salt and pepper. Stir in the garlic and parsley, then the bread crumbs. Let sit for 2 minutes. Add the beef and sausage and mix to combine. Form the meat mixture into 1 1/2-inch balls (about 20 total) and place on the foil-lined baking sheet. Broil until cooked through, 6 to 8 minutes. Meanwhile, bring a large pot of water to a boil. Add 2 teaspoons salt, then the broccoli rabe, and cook until just tender, 3 to 4 minutes. Drain, squeezing out excess water. Transfer to a cutting board and roughly chop. Reduce oven temperature to 425 degrees F. On a lightly floured surface, shape the dough into four 8-inch rounds. Dividing evenly, top half of each round with the meatballs, broccoli rabe, cherry peppers, and provolone. Fold the dough over the filling and pinch the edges to seal. Place on the parchment-lined baking sheet and brush with the oil. Bake until golden brown, 20 to 25 minutes. Serve with the marinara sauce for dipping, if desired.