Heat oven to 375° F. Place cupcake liners in muffin tin.
Place cereal in a blender or food processor and coarsely crush.
Add crushed cereal to a medium bowl and stir in buttermilk; let stand 5 minutes.
Add oil, eggs, and vanilla into cereal; whisk to combine. Add flours, sugar, cocoa, baking soda, and salt; stir just until moistened.
Gently fold in raspberries (do not thaw).
Divide batter evenly among muffin cups.
Bake 20-25 minutes or until a toothpick inserted into the center of a muffin comes out clean.
Immediately remove muffins from pan and allow to cool on a wire rack before serving.