• Line a large baking sheet with parchment paper. Unless you are a wiz at making perfectly uniform circles, place a template with 1 1/2" circles under the parchment.  I made one in MS Word with three rows of five circles and printed off two copies of it
• Process confectioner's sugar and almond flour in a food processor until finely ground. Sift the mixture through a sieve. If there are more than 2 tablespoons of large chunks left in the sieve, grind them and sift again. Set this mixture aside.
• Use a stand mixer with a whisk attachment and beat egg whites at medium speed until frothy. Reduce the speed to low and gradually add the granulated sugar, 1 tablespoon at a time. Add vanilla. Increase the speed to high and beat until very stiff peaks form, about 5 minutes.  Note:  If you don't have a stand mixer a handheld mixer will work.
• Gently add half the almond flour mixture to the egg whites. Using a rubber spatula, gently fold the almond flour mixture into the egg whites until the ingredients are just combined. Add second half of the almond flour mixture and continue to fold the mixture until it has loosened and falls in a ribbon from the spatula.  Note:  I watched a bunch of YouTube videos to really understand the consistency you need.
• Fill a pastry bag with the batter. Cut the tip of the bag off (alternatively you can use a 1/2" round tip.  I didn't find it necessary).  Using the template as a guide, pipe circles onto the parchment paper.
• Tap the bottom of each sheet on the work surface to release trapped air bubbles (just drop it about 5 or 6 inches from your work surface).  Rotate the cookie sheet 1/4 turn and do it again.  Repeat this two more times.  Top with sprinkles. Let the cookies stand at room temperature for 30-60 minutes. This allows the cookies to develop their crusts which in turn helps the cookie develop their signature "feet" during baking.
• Preheat oven to 325F. Bake the macarons for 11 to 13 minutes, until set but not browned.
• Transfer the baking sheet to wire racks and let the macarons to cool completely on the pans. 

Buttercream frosting

• In the bowl of a stand mixer fitted with the paddle attachment, whip the butter until it is a pale color, approximately 3 minutes. 
• Sift in the powdered sugar, and mix on medium speed until well combined. 
• Mix the milk and vanilla together and slowly add to butter mixture untiI the frosting is light and fluffy, and a pipeable consistency. 
• Transfer to a pastry bag and cut the tip of the bag off (alternatively you can use a 1/2" round tip.

Assembly

• Place half of the cooled cookies upside down.  You may need to pair the cookies if your sizes aren't consistent.
• Pipe a teaspoon of filling onto each of the upside-down cookies. Top with the remaining cookies. Chill in an air tight container in the refrigerator for 24 hours before serving.