Dice the onion into 1/4-inch pieces and set aside. Heat a large skillet over medium-high heat and add the ground chicken, breaking it apart with a spoon as it cooks. Cook for 5-7 minutes until the chicken is fully cooked through with no pink remaining and has begun to brown slightly. This browning step builds flavor through the Maillard reaction, which is crucial for depth even in a slow-cooked dish. Drain any excess fat from the cooked chicken if needed.

Transfer the cooked chicken from Step 1 to your crockpot along with the diced onion. Add both cans of diced tomatoes (regular and with green chiles), the drained and rinsed kidney beans, and all the dry spices: chili powder, cumin, salt, garlic powder, and cayenne pepper. I like to add the spices gradually and taste as I go—you can always add more cayenne if you prefer extra heat, but you can't remove it once it's in. Stir everything together thoroughly to distribute the spices evenly throughout the mixture.

Cover the crockpot and cook on high for 4 hours. The long, gentle cooking allows the spices to fully infuse into the liquid and the flavors to deepen and meld together. I recommend stirring once at the 2-hour mark to ensure even cooking, though this isn't absolutely necessary. The chili is ready when it's hot throughout and the flavors have become rich and cohesive.