Combine flour, salt, and red pepper flakes in large bowl; add Cheddar cheese. Toss until cheese is coated. Pour in melted butter; stir until mixture is moist and crumbly. Add rice cereal and knead by hand until dough is well blended.
Roll dough into small 1/2-inch balls; arrange on a baking sheet. Flatten each ball with a fork.
Bake in the preheated oven until light and crispy, about 30 minutes.