Heat a large skillet over medium-high heat and drizzle in the oil. Once hot, add the ground turkey and cook, breaking up with a wooden spoon until browned and crispy, about 5 to 7 minutes. Throw in the onion, garlic, garlic salt, chili powder, and black pepper. Toss to evenly combine. Cook for about 3 to 5 minutes or until the veggies have softened.
In the bowl of a slow-cooker, combine the cooked turkey, diced tomatoes, beans, tomato sauce, corn and green chilies (if using). Stir to fully incorporate. Cover and cook on low for 6 to 7 hours or on high for 2 to 4. Serve with suggested toppings.