In a separate bowl, at high speed, beat egg whites until they begin to foam. Continually beating then slowly pour in the sugar and beat just until stiff peaks form.
Add about half of the sifted coffee flour mixture into the egg white mixture and gently fold in with a spatula. Once incorporated, add remainingflour mixture and continue to gently fold until well the mixture flows like honey.
Transfer the batter to the preparing piping bag. Pipe the batter forming about 1½ inch circles. Space the macarons about an inch apart.
Pick up the baking sheet and drop onto a flat surface. Repeat 3-4 times to release all air bubbles rotating the baking sheet.
Let the macaron shells sit at room temperature for at least 30 minutes to 1 hour, until the macarons shells form a glossy layer. (You will be able to run your finger along the top of the macaron smoothly and the batterwon’t stick to your hand.)
Preheat the oven to 325°F.
Bake the macarons for about 12 minutes, until the macarons form feet and the shells don't stick to the parchment paper.
Allow the macarons to cool before removing them from the parchment paper for easier removal.
In a small bowl, combine the boiling water and instant coffee and mix. Let cool.
Meanwhile, combine butter and cream cheese in a bowl. Blend with a mixer until creamy, add the powdered sugar and cooled coffee and mix. Add the heavy whipping cream and mix until combined. Transfer the filling into a piping bag with a round top.
Pipe the cream onto a macaron shell and top with another shell to form a sandwich.
Repeat with the remaining macaron shells and buttercream.