Blackberry and Strawberry Macarons

Blackberry Macarons (makes about 30)

90 gr egg whites (about 3) preferably aged 3-5 days in the fridge
30 gr granulated sugar
200 gr powdered sugar
110 gr almonds

a few drops of purple gel-based food coloring 

Filling: Blackberry Swiss Meringue Buttercream 

In a stand mixer fitted with the whisk attachment, whip the egg whites to a foam, gradually add the sugar until you obtain a glossy meringue. Add the food coloring.  Do not over beat your meringue or it will be too dry. 

In a separate bowl sift the confectioner's sugar and almond flour.  Add them to the meringue, give it a quick fold to break some of the air and then fold the mass carefully until you obtain a batter that flows like lava or a thick ribbon. Give quick strokes at first to break the mass and slow down. The whole process should not take more than 50 strokes. Test a small amount on a plate: if the tops flattens on its own you are good to go. If there is a small beak, give the batter a couple of turns.

Fill a pastry bag fitted with a plain tip (Ateco #807 or #809) with the batter and pipe small rounds (1.5 inches in diameter) onto parchment paper or silicone mats lined baking sheets. 
Preheat the oven to 300F. 

Let the macarons sit out for 30 minutes to an hour to harden their shells a bit.  Bake for about 15-20 minutes, depending on their size.  Let cool. If you have trouble removing the shells, pour a couple of drops of water under the parchment paper while the sheet is still a bit warm and the macarons will lift up more easily do to the moisture. Don't let them sit there in it too long or they will become soggy.

Once baked and if you are not using them right away, store them in an airtight container out of the fridge for a couple of days or in the freezer. To fill: pipe or spoon about 1 big tablespoon of butterceam in the center of one shell and top with another one.