Preheat oven to 425°F and grease a 6-count donut pan with nonstick cooking spray.

Place the cereal in a large zip top bag and crush until mostly broken up into fine pieces.

In a large bowl, whisk together the flour, sugar, baking powder and salt.

In a separate bowl, mix buttermilk, egg, and oil with a fork until everything is combined.

Add wet ingredients and crushed cereal to the large bowl with the dry ingredients, then mix until everything is evenly combined.

Place the batter in a piping bag (or large zip top bag with a corner cut off) and pipe the batter into the donut pan so each section is about half full.

Bake the donuts in the preheated oven for 7-9 minutes, until the donuts have risen, and a toothpick comes out clean.

Once the donuts have baked and cooled for 5 minutes, invert the pan over a wire cooling rack so the donuts fall out and let them cool completely.

Sift the powdered sugar into a large bowl and whisk in the buttermilk and vanilla. Whisk until smooth, the glaze will probably seem too thick but the thicker the glaze the less likely it is to run off the donut.

Once donuts have cooled, dip one side of each donut into the glaze then garnish with more cereal. Let the glaze set then serve.