Stovetop Method
Heat a large pot over medium heat. Add the ground bison and cook until browned, breaking it into small pieces.
Add diced onions and garlic. Cook until softened and fragrant, about 3-4 minutes.
Stir in red and green bell peppers. Cook for 2 minutes.
Add diced tomatoes, kidney beans, black beans, pumpkin puree (if using), and spices. Mix well.
Pour in the broth, bring to a simmer, then reduce heat to low. Cover and cook for 25-30 minutes, stirring occasionally.
Taste and adjust seasoning as needed. Serve hot with toppings.
Crockpot / Slow Cooker Method
Brown bison in a skillet for better flavor.
Add all ingredients to the slow cooker.
Cook on low for 6-8 hours or high for 3-4 hours.
Stir occasionally, taste, and adjust seasoning before serving.