Mix the butter and cheese together thoroughly with a hand mixer, stand mixer, or sturdy fork. Add the chili powder, onion, cumin, salt, and pepper, and mix well. Gradually add the flour, and blend well. Form into two logs, about 1 ½-inches in diameter. Wrap the logs in waxed paper, and chill for several hours or overnight.
Remove waxed paper, and slice each roll thinly into ¼-inch coins. Place coins on a cookie sheet lined with parchment paper or a Silpat, and bake in a preheated 400° F oven for 10 minutes, or until lightly browned.
Serve immediately, or place crackers on a cooling rack, and once cooled, store in an airtight container.