Preheat oven to 350°F, 177°C, or gas mark 4 and place cupcake liners in the cupcake tin.
Whisk the flour, baking soda, baking powder and salt and then sift into a large bowl and set aside.
In a stand mixer with a paddle attachment on medium high speed, cream the butter and sugar until light. Then add the eggs one at a time waiting a minute after easy egg. Add the sour cream and vanilla.
Reduce the speed to low and add half of the flour mixture, mix until just incorporated, then add the buttermilk mixing until just combined, and follow up with the remaining flour mixture.
Fill cupcake papers about ⅔ the way up or use a 3 tablespoon cookie scoop. Bake for 15-18 minutes or until the springy to the touch. Allow to cool completely.
Making the Buttercream:
While the cupcakes are cooking in a stand mixer with a paddle attachment cream the butter and cream cheese on medium high.
Reduce the speed to low and add the powdered sugar and salt. Once all of the sugar has been incorporated increase the speed to high until the frosting is light and fluffy.
In a pan cook the coconut until about half of it has toasted and remove from the heat.
Creating the nest:
Using a piping bag you will want to to make a thin disk of icing on the top of the cupcake and then create a well by piping another ring or two just around the edges of the cupcake.
Gently press sides of the icing into a bowl of the toasted coconut and then place the Cadbury eggs in the well in the middle.