• In a large mixing bowl using an electric whisk cream together on medium-high speed ½ cup of soft unsalted butter with 1 cup of brown sugar and ½ cup of granulated sugar until combined.
• Add 2 eggs ( one egg at a time) and beat well. Now lowering the speed blend in 1 cup of greek yogurt, ¼ cup of whole milk, and 2 tsp of vanilla extract. In a separate small cup combine 1tbsp of apple vinegar with 1 tsp of baking soda. Then gently incorporate it in the batter.
• Now add ½ cup of cocoa powder. Then add 2 ½ cups of all-purpose flour previously mixed with 1 tsp of salt. Mix well.
• Preheat the oven to 350 °F.  Prepare two baking sheets, lining them with parchment paper. Set aside.
• Drop with a 1-oz cookie or ice cream scoop, dough onto the prepared baking pans ( 12 cakes per pan), flattening slightly if needed. Make sure you arrange cakes about 2 inches apart.
• Bake for about 15 -17 minutes in a preheat oven at 350 °F.

For the Filling:

• In a large mixing bowl cream together on a medium speed ½ cup of softened unsalted butter, 4 oz of cream cheese, and 1 - 1 ½ cups of icing sugar. Then gradually add 1 tsp of vanilla extract, and 2 tbsp of whole milk. Continue whisking until light and fluffy.

Assemble the Whoopie Pies:

• When cakes cooled completely transfer cream cheese frosting to a disposable pastry bag. Pipe frosting on the flat side of the cake and sandwich with another cake, and lightly squeeze together. Repeat for all cakes.