This ciabatta sandwich is loaded with spicy salami, cheese, onions, and peppers, then topped with mozzarella cheese and baked until hot and toasty.
Combine cipollini onions, vinegar, and salt in a food processor or blender; puree until nearly smooth. Set aside for 1 hour.
Heat olive oil in a large skillet over medium-high heat; cook and stir onion, red bell pepper, and goat horn peppers in the hot oil until onion softens and begins to turn golden, 7 to 8 minutes. Remove onion mixture to a plate. Cook and stir coppa ham, soppressata, pork loin, and mortadella in the same skillet until warmed through and lightly browned, about 5 minutes.
Spread each ciabatta roll with 1 tablespoon garlic basil spread, 1 tablespoon garlic roasted tomato sauce, 1 tablespoon artichoke aioli, and 1 tablespoon cipollini onion mixture. Top with 1/4 pound mozzarella cheese. Evenly distribute the soppressata mixture among the 4 sandwiches and top with equal amounts of the bell pepper mixture.
Arrange sandwiches on a baking sheet and bake in the preheated oven until the cheese is melted and the bread is toasted, 3 to 4 minutes.
Per Serving: 2241 calories; protein 117.6g; carbohydrates 251.3g; fat 81.7g; cholesterol 234.2mg; sodium 6549.1mg.