Trattoria Veggie Paninis

Toss bell pepper on a baking sheet with olive oil, salt, and pepper. Roast until softened and lightly charred, 18-20 minutes.

Meanwhile, heat a drizzle of oil in a large, preferably nonstick, pan over medium-high heat. Add onion; cook, stirring occasionally, until softened, 8-10 minutes. Stir in vinegar and 1 tsp sugar (2 tsp for 4 servings). Cook, stirring, until caramelized and jammy, 2-3 minutes. Season with salt and pepper. Turn off heat; transfer to a small bowl. Wash out pan.

While veggies cook, in a small pot, combine marinara sauce, stock concentrate, ¾ cup water (1½ cups for 4 servings), ½ tsp sugar (1 tsp for 4), and a big pinch of salt. Bring to a boil over medium-high heat. Once boiling, reduce heat to medium low and simmer for 4-5 minutes. Stir in cream cheese until melted. Cover and continue to simmer until ready to serve.

Heat pan used for onion over medium heat. While pan heats, place 3 TBSP butter (5 TBSP for 4 servings) in a small microwave-safe bowl; microwave until just softened, 10-20 seconds. Spread one side of each slice of bread with softened butter. Place buttered sides down on a work surface. Top half the slices with half the mozzarella, all the veggies, and remaining mozzarella. Complete sandwiches with remaining slices of bread, buttered sides up; press firmly.