Preheat the oven to 400°F.

On a rimmed baking sheet, place the 10 ounces cauliflower florets, 10 ounces broccoli florets, and the 1 large red bell pepper pieces. Drizzle with 2 tsp olive oil, sprinkle with 1/4 tsp kosher salt and black pepper to taste, and toss to coat. Spread the vegetables into an even single layer.

Bake the vegetables for 20 minutes.

While the vegetables bake, combine 1/4 cup breadcrumbs, 1/4 cup chicken broth, 1 large egg, 1 tsp fennel seeds, 1/2 tsp sweet paprika, 1/2 tsp crushed red pepper, and the remaining 3/4 tsp kosher salt in a large bowl. Mix until well combined.

Add 1 lb (93% lean) ground turkey to the breadcrumb mixture. Use a fork to gently mix until uniform, taking care not to overwork the meat. Form the mixture into 16 evenly sized meatballs.

After the vegetables have baked 20 minutes, remove the sheet from the oven and stir the vegetables. Push the vegetables to one side of the sheet to make room, and arrange the 16 meatballs on the empty side with a little space between each.

Return the sheet to the oven and bake until the meatballs are cooked through, about 18–20 minutes (internal temperature should reach 165°F).

Remove from the oven, let rest a couple of minutes, then serve hot.