Slow-Cooker Sweet-and-Spicy Chicken

ground cumin

ground cinnamon

Coarse salt and ground pepper

chicken leg quarters (2 1/2 pounds total)

extra-virgin olive oil

medium yellow onion, cut into 1/2-inch wedges (root end left intact)

garlic cloves, minced

-inch piece peeled fresh ginger, sliced into rounds

diced tomatoes

raisins