In a large bowl whisk together the flour, cocoa, salt, baking powder and baking soda.
Cream the butter and sugar together in a medium bowl. Add the eggs one at a time making sure to mix thouroughly. Mix in the sour cream, vanilla and milk.
While mixing on low speed add the wet ingredients to teh dry and mix until just combined.
Scoop the batter into cupcake papers filling 2/3 the way up.
Bake at 350 for 20-25 minutes or until the centers are springy to the touch.
For the Reduction
Place the ingredients in a small sauce pan on medium low heat.
Mash the berries with the back of a spoon or muddler and stir occasionally.
You want to reduce the amount of liquid, intensify the flavor, and thicken the liquid so aim to cook until the mixture is reduced at least by half.
Strain the reduction and set aside to cool.
For the Buttercream
Beat the egg whites, salt, and 1/3 cup of sugar until soft peaks form. At the same time in a medium saucepan add the remaining sugar and 1/3 cup water and place on medium-high heat. Stir until sugar melts and becomes clear. Maintain a medium high heat until temperature reads 235-240F.
Drizzle the sugar into the mixer (remembering the egg whites should be at the soft peak stage). Run mixer until meringue is body temperature. 10-15 minutes.
Add room temperature butter into running mixer one tablespoon at a time. Beat until butter is combined and mixture has reached a silky consistency
Mix in the cooled berry reduction and pipe onto cupcakes using an 869 tip. Top with a whole raspberry.