Heat a large pot over medium heat and add a splash of oil.
Sauté the diced onion until translucent, about 5 minutes.
Add minced garlic and cook for another minute until fragrant.
Stir in the chili powder and cumin, cooking for 1-2 minutes.
Add the pumpkin puree, stirring well to combine with spices.
Pour in the diced tomatoes and their juices, mixing thoroughly.
Add the drained beans and corn, stirring to incorporate all ingredients.
Season with salt and pepper to taste.
Bring the chili to a simmer and reduce heat to low.
Cover and let cook for 20-30 minutes, stirring occasionally.