Mix together flour, cornstarch, baking soda and finely crushed cereal. Set aside.

Add butter and sugar to a mixer and beat well until fluffy, about 3-5 minutes. Add eggs and vanilla and beat well until combined. Add dry flour and cereal together and beat just until combined. Fold in whole cereal.

Refrigerate for 30 minutes.

Preheat oven to 350 and line a baking sheet with parchment paper. Use a ⅓ cup measuring cup and press dough into measuring cup. Drop 6 cookies onto prepared baking sheet and press each one lightly to flatten until cookie is about ½" thick.

Bake for 15-17 minutes or until cookies just begin to brown on the bottom. Remove from oven and let stand for 2 minutes on a baking sheet, before removing and placing onto a cooling rack to cool completely.