Preheat oven to 350F.
Roughly chop onions, carrots, bell peppers; mince garlic.
Add chopped vegetables, garlic, tomatoes, and spices to a casserole dish. Stir to combine and coat. Bake for 20mins.
Remove from oven and add beans and BBQ sauce. Stir to combine and coat. Return to oven and bake for an additional 40mins.