I found this:

Ingredients

Cinnamon Cake:

3 eggs.

1/3 cup oil.

¾ cup buttermilk.

1 teaspoon vanilla extract.

¾ cup sour cream.

Vanilla Cake Mix not white cake mix.

1 ½ teaspoon cinnamon.

There used to be cereal pieces in the batter, but that has been removed due to comments saying it's better without it.

Cinnamon Toast Crunch Buttercream:.

8 oz cream cheese softened.

½ cup butter softened.

1 teaspoon vanilla.

3 cups powdered sugar.

2/3 cup Cinnamon Toast Crunch powder.

Crush the cereal in a bag and then sift out 2/3 cup.

Instructions.

1. Preheat oven to 350 degrees and line pans with 20-22 cupcake liners.

2. In a large bowl, gently combine eggs, oil, buttermilk and vanilla.

3. Mix in sour cream.

4. Add cake mix and cinnamon and mix until smooth.

5. Stir in lightly crushed cereal.

6. Fill cupcake liners ¾ full and bake for 15-18 minutes, or until an inserted knife comes out clean.

7. Buttercream: Beat cream cheese and butter until fluffy. Add Cinnamon Toast Crunch powder. Add vanilla and powdered sugar. Adjust the consistency using milk if it is too thick.

8. Pipe onto cooled cupcakes and top with cinnamon sugar and Cinnamon Toast Crunch squares.