A casserole with the flavors of a classic sloppy joe but with none of the messy eating.
Ingredients
1 large yellow onion (about 10 ounces)
2 small red bell peppers (about 6 ounces each)
6 large cloves garlic, minced
4 tablespoons olive oil, divided
1 3/4 teaspoons kosher salt, divided
2 1/2 pounds lean ground beef
2 (15-ounce) cans tomato sauce
3/4 cup ketchup
2 tablespoons apple cider vinegar
2 tablespoons packed light brown sugar
2 teaspoons prepared yellow mustard
2 teaspoons Worcestershire sauce
8 to 12 ounces shredded Mexican blend cheese (2 to 3 cups)
12 slider buns or soft dinner rolls
4 tablespoons (1/2 stick) unsalted butter
1 tablespoons poppy seeds
Instructions
Dice 1 large yellow onion (about 2 cups). Trim and finely chop 2 small red bell peppers (about 2 cups). Mince 6 large garlic cloves (about 3 tablespoons).
Arrange a rack in the middle of the oven and heat the oven to 375ºF. Heat 2 tablespoons olive oil in a Dutch oven or large pot over medium-high heat until shimmering. Add the onion and bell peppers, and season with 1/4 teaspoon of the kosher salt. Cook, stirring occasionally, until the onion is translucent and the peppers are just tender, about 7 minutes.
Add 2 tablespoons of the garlic and cook, stirring often, until fragrant and light golden brown, about 2 minutes. Scrape into a 9x13-inch baking dish.
Return the pot to high heat. Add 2 1/2 pounds lean ground beef and season with the remaining 1 1/2 teaspoons kosher salt. Cook, breaking up the beef into smaller pieces with a wooden spoon, until cooked through, 5 to 8 minutes. Meanwhile, place 2 (15-ounce) cans tomato sauce, 3/4 cup ketchup, 2 tablespoons apple cider vinegar, 2 tablespoons packed light brown sugar, 2 teaspoons prepared yellow mustard, and 2 teaspoons Worcestershire sauce in a medium bowl.
Add the tomato sauce mixture and stir to combine. Reduce the heat to medium-high and bring to a simmer, stirring frequently. Reduce the heat to medium and simmer until the sauce is slightly thickened, about 5 minutes.
Scrape into the baking dish and stir to combine with the onions and peppers. Wipe off any splatters on the sides of the baking dish with a paper towel. Sprinkle evenly with 8 to 12 ounces shredded Mexican cheese (2 to 3 cups). Arrange 12 slider buns or dinner rolls on top of the sloppy joe mixture in a single layer.
Melt 4 tablespoons unsalted butter in a small saucepan over medium heat or in the microwave. Remove the pan from the heat. Add the remaining 1 tablespoon garlic and 1 tablespoon poppy seeds and stir to combine.
Brush the butter mixture onto the slider buns. Bake until the sloppy joe mixture is bubbling and the buns are golden-brown and crisp, 10 to 15 minutes; check at 8 minutes and loosely cover with aluminum foil if the rolls are browned before the filling is hot.
