Ground beef and cauliflower combine to create a hearty weeknight casserole that both kids and adults will love. Serve with tortilla chips and sour cream.
Position rack in upper third of oven. Preheat broiler to high.
Heat oil in a large oven-safe skillet over medium heat. Add onion and bell pepper; cook, stirring, until softened, about 5 minutes. Add beef and cauliflower; cook, stirring and breaking the beef up into smaller pieces, until it is no longer pink, 5 to 7 minutes. Stir in garlic, chili powder, cumin, oregano, salt and chipotle; cook until fragrant, about 1 minute. Add tomatoes and their juices; bring to a simmer and cook, stirring occasionally, until liquid is reduced and the cauliflower is tender, about 3 minutes more. Remove from heat.
Sprinkle cheese over the beef mixture and top with sliced jalapeños. Broil until the cheese is melted and browned in spots, 2 to 3 minutes.