Snickers Cupcake

1/2  cup  Dutch-process cocoa powder
1/2  cup  hot water
 2    cups  all-purpose flour
3/4  teaspoon  baking soda
3/4  teaspoon  baking powder
3/4  teaspoon  coarse salt
16   tablespoons  unsalted butter -- 2 sticks
1.5  cups  granulated sugar
2     large  whole egg -- room temperature
1     large  whole egg yolk -- room temperature
1.75  teaspoons  vanilla extract
 2/3  cup  sour cream -- room temperature
 16   tablespoons  unsalted butter -- 2 sticks; 8 oz
  1/2  teaspoon  salt
  2     cups  dark brown sugar -- packed
  1/2  cup  milk
  2      teaspoons  vanilla extract
  4    each  Snickers candy bars -- 12 fun sized bars, chopped
  3.5  cups  confectioner's sugar
  2     each  Snickers candy bars -- 8 fun sized bars, chopped

TO MAKE THE CUPCAKES

Preheat the oven to 350 F.  Line muffin pans with 20 paper liners.

In a 2-cup glass measuring cup, whisk together the cocoa powder and hot
water until smooth, then set aside.

In a medium bowl, whisk together the flour, baking soda, baking powder,
and salt, then set aside.

In a medium saucepan over medium heat, combine the butter and sugar,
stirring occassionally until the butter is melted and the mixture is
combined.  Remove from the heat and transfer to the bowl of a stand mixer
fitted with a paddle attachment.  Beat on medium-low speed until the
mixture is cool, about 4-5 minutes.

Add eggs and egg yolk, one at a time, beating until each is incorporated,
scraping down the sides of the bowl as needed.  Mix in vanilla extract and
cocoa mixture until incorporated.  With the mixer on low speed, add in the
dry ingredients in two batches, alternating with the sour cream, beating
just until combined.

Fill the cupcake papers three-quarters full.  Bake for 18-20 minutes,
roating the pans after 10 minutes.  Cupcakes are done when a toothpick
comes out clean.  Allow the cupcakes to cool for 5-10 minutes before
transferring to a wire rack to cool completely.

TO MAKE THE FILLING:  Melt the butter in a heavy-bottomed saucepan over
medium heat.  Stir in the salt and brown sugar and heat the mxture to
boiling, stirring constantly.  Cook over low heat for 2 minutes, until the
sugar is totally dissolved.  Stir in the milk and return to a boil,
stirring constantly.  Remove the pan from the heat and stir in the vanilla
extract.  Cool to lukewarm, about 30-40 minutes, stirring occasionally.

Once the cupcakes have cooled, use a paring knife or apple corer to cut
out a small circle in the center of each cupcake.  In a medium bowl,
combine the chopped Snickers bars and 1/4 cup of the cooled caramel sauce.
 Toss to coat the candy bars, then drop a spoonful of the mixture into
each cupcake.  Reserve 3 tablespoons of caramel sauce for drizzling over
each cupcake.

TO MAKE THE FROSTING:  Transfer remaining caramel sauce to the bowl of a
stand mixer fitted with the paddle attachment.  Add powdered sugar and
beat on medium-high speed until light and fluffy, about 3-4 minutes.
Adjust consistency with a little more milk (if it's too thick) or
confectioner's sugar (if it's too thin), if needed.

Transfer the frosting to a pastry bag fitted with a decoratvie tip.  Pipe
a spiral of icing, beginning at the outer edge and working inward.
Drizzle the frosted cupcakes with caramel sauce and garnish with chopped
Snickers bars.