To make the Cupcakes: place oats and liquid ingredients into a blender or food processor. Blend until oats are smooth. Pour mixture into a large bowl, and mix with the rest of the ingredients until combined. Pour into cupcake liners and bake for 22-25 minutes, or until a toothpick comes out clean. Let cool completely before frosting.
To make the Frosting: Place the chocolate in a medium microwave safe bowl, and microwave for 1 1/2 -2 minutes, or until melted, stirring every 30 seconds. Once melted, mix yogurt, stevia, and peppermint extract into chocolate until a thick 'frosting' texture forms. Fold in whipped topping. Chill until ready to frost cupcakes.