Heat olive oil in a pan over medium heat.
Add a pinch of salt while sautéing onions to build a deeper flavor base.
Add diced onion and sauté until soft and translucent.
Stir in minced garlic and cook for another minute.
Transfer the mixture to the slow cooker.
Add cannellini beans and black beans.
Add pumpkin chunks and crushed tomatoes.
Sprinkle in chili powder, cumin, and cayenne pepper.
Mix everything well to combine.
Cook on low for 6–8 hours or high for 3–4 hours.
Avoid frequent stirring to maintain consistent heat; stir once or twice if needed.
Taste and adjust salt and pepper before serving.
Serve warm with your favorite toppings.