Preheat oven to 400°F. Spread cauliflower florets in a single layer on a parchment-lined baking sheet and lightly spray with cooking spray. Roast for 30 minutes. Cool slightly, then transfer to a food processor (or blender). Add 1 cup of chicken broth and process until smooth. Transfer to a bowl, season with salt and pepper, and set aside.

Heat the ground beef in a large skillet on medium-high heat until browned. Transfer beef to a paper towel-lined tray to drain excess fat.

Add diced onion, minced garlic, and diced peppers to the same skillet (still on medium-high heat). Cook, stirring frequently, for about 3 minutes. Stir in cumin and paprika and cook for 1 minute more, stirring constantly. Return the cooked beef to the skillet. Stir in the remaining 1 cup of chicken broth, diced tomatoes, chopped olives, and balsamic vinegar. Cook for 6 minutes, or until the mixture has thickened slightly and reduced by half. Season with salt and pepper to taste. Transfer the beef mixture to an 8 or 9-inch square baking dish, spreading it out evenly.

Spoon the prepared cauliflower puree over the beef mixture as evenly as possible.

Cover the baking dish with foil and bake for 20 minutes at 400°F. Remove the foil and bake for an additional 10 minutes, or until the topping is lightly golden and heated through. Serve hot.