Summer Fresh Dessert

This dessert is a basic vanilla cupcake with buttercream frosting, but that's not all. No, we decided to put a chocolaty spin on things. May we introduce you to: Nutella Cup Cakes! The rich, creaminess of the frosting, the melting chocolate, and the fresh, warm cake make for a lovely end to a lovely meal. This recipe yields 4 cakes.
Ingredients For Cupcakes
1 egg
2/3 stick of butter
1/3 cup berry/caster/super fine sugar
1/6 buttermilk*
1/2 cup self raising flour**
1/3 teaspoon vanilla extract
Two tablespoons nutella brand hazelnut chocolate spread
(*Also, use 1/6 cup milk and add the juice of half a lemon. Wait for it to curdle, then use as buttermilk. **Use 1/2 teaspoon baking powder, a pinch of salt, and 1/2 cup of regular flour.)
Directions For Cupcakes
Heat the oven to 320 F, or 160 C. If using a silicone pan, grease and use without papers. If using a metal pan, use papers. In a bowl, lightly beat eggs. Then add the butter and sugar to the mixture, and mix until light and fluffy. Add the buttermilk/curdled milk, flour/baking powder, and vanilla in an electric mixer on medium for two minutes, until light and creamy. Pour in the bottom half of all the cupcakes. Then add 1/2 a tablespoon of nutella. Fill the rest of the cupcake to cover. Bake for 18-20 minutes. While it bakes, follow the frosting recipe.
Ingredients For Frosting
2/3 cup powdered sugar
1 1/3 stick butter
4 drops vanilla extract, or 1/2 a teaspoon
Directions For Frosting
Put 2/3 stick of butter, 1/3 cup powdered sugar, and two drops vanilla into a a mixing bowl. Mix in an electric mixer or with a wooden spoon until it looks the consistency you enjoy. Add the rest of the ingredients and mix till the consistency is thick and creamy. When the cakes have cooled entirely, frost them. If you wish, use a piping bag, a plastic bag, or a plastic bag with a frosting tip inside.