Step 1

Heat oil in a large skillet over medium heat; stir in bell peppers and onions. Cook and stir until the onion has softened and turned translucent, about 5 minutes. Add garlic and cook until fragrant, 1 to 2 minutes. Transfer to a slow cooker.

Step 2

Add zucchini, yellow squash, and spinach to the slow cooker; stir to combine. Mix in diced tomatoes, corn, black beans, kidney beans, garbanzo beans, tomato paste, vegetable broth, chili powder, oregano, and cumin. Season with salt and pepper.

Step 3

Cook on Low for 4 to 5 hours.