Step 1: In a large skillet or Dutch oven, heat olive oil over medium-high heat. Add chopped onion, green bell pepper, and red bell pepper. Sauté until softened, about 5-7 minutes. Push vegetables to one side of the pan.
Step 2: Add the ground beef to the skillet. Break it up with a spoon and cook until fully browned. Drain any excess fat.
Step 3: Sprinkle the browned beef and vegetables with chili powder, cumin, smoked paprika, dried oregano, and garlic powder. Stir constantly for 1 minute until fragrant.
Step 4: Pour in the beef broth and scrape up any browned bits from the bottom of the pan with a wooden spoon. This deglazing step adds rich flavor to the slow cooker beef chili recipe.
Step 5: Transfer the beef mixture to your slow cooker. Add the diced tomatoes (undrained), crushed tomatoes, tomato paste, rinsed and drained kidney beans, rinsed and drained pinto beans, and the bay leaf. Stir gently to combine all ingredients.
Step 6: Cover your slow cooker and cook on the LOW setting for 6 to 8 hours, or on the HIGH setting for 3 to 4 hours. The longer cook time on low allows for maximum flavor development.
Step 7: Once cooked, remove and discard the bay leaf. Taste the chili and adjust seasonings as needed with salt and freshly ground black pepper.
Step 8: For best flavor, let the chili rest for 15-20 minutes before serving. Serve hot with your favorite toppings.