Line astandard-sized 12 cups muffin tin with cupcake liners.
For cupcakes: in a large-sized bowl, sift together flour, cocoa powder,baking powder, and salt.
In another large-sized bowl, add sugar and butter and with an electricmixer, whisk until fluffy and light.
Add eggs and whisk until well blended.
Add vanilla extract and beat well.
Add flour mixture in two batches, alternating with sour cream and beat onlow speed until just blended.
Place mixtureinto the prepared muffin cups.
Transfer themuffin tin into the oven and bake for approximately 21-25 minutes or until awooden skewer inserted in the center of the cupcakes comes out clean.
Remove themuffin tin from oven and place onto a cooling rack to cool for at least 5minutes.
Then invert thecupcakes onto wire rack to cool completely before icing.
For icing: in a bowl, add butter and beat until smooth.
Slowly add confectioners' sugar and beat until smooth.
Add milk and stir to blend.
Spread icing over each cupcake evenly.
Decorate each cupcake with candy corn and sprinkles and serve.