Sift together the almond flour, powdered sugar, and strawberry powder through a fine mesh sieve, discarding the pieces left in the sieve.
Prepare a double boiler, making sure that the water doesn’t touch the bottom of the bowl. Add the egg whites and sugar to the double boiler bowl, whisking until the egg whites are frothy and the sugar is dissolved. You can test this with your fingers. Dip a finger into the egg white mixture and rub it on another finger; if you don’t feel sugar crystals, it’s good to go. Alternatively, you can test this with a thermometer; the temperature should be around 150F.
Add the egg white/sugar mixture to a large bowl and use a handheld electric mixer to beat until it forms stiff peaks.
Beat the strawberry extract and red gel food coloring into the whipped egg whites.
Use a rubber spatula to gently fold 1/3 of the almond flour mixture at a time into the egg whites. Be careful not to over-mix.
Line 2 large baking trays with parchment paper or silpat liners. Fit a piping bag with a round tip, and transfer the batter to the piping bag. Pipe the batter into 3/4-inch circles about 1 inch apart.
Tap the trays firmly against the countertop a few times to release any air bubbles.
Let the piped cookies sit at room temperature until they form a skin and feel dry on top, about 30 to 60 minutes.
Preheat the oven to 325F.
Bake the trays one at a time until the macarons develop a puffed “foot” on the bottom and are light golden around the outside, about 15 minutes, rotating the tray once every 5 minutes.
Let the cookies cool completely before removing from the baking tray.
For the Vanilla Buttercream:
Beat together all ingredients in a large bowl until light and fluffy, adding enough milk to achieve the right consistency.
To Assemble the Macarons:
Match up similar sized and shaped macarons into pairs.
Fit a piping bag with a star tip, and transfer the buttercream to the piping bag. Pipe a ring of buttercream on the bottom cookie of each cookie pair. Place the matched cookie on top to form sandwiches.
To Decorate the Macarons:
Place the macarons on a wire rack on top of a parchment-lined baking tray.
Melt the white candy melting wafers in a microwave or double boiler. Stir until smooth. Transfer the melted candy to a zip-top plastic bag and snip off one corner. Drizzle the melted candy decoratively on top of each macaron. Before the candy drizzle sets, sprinkle a tiny bit of finely crushed freeze dried strawberries on each.
Let the candy set before serving.
If you don’t have strawberry powder, you can make it with freeze dried strawberries. To do so, add about 9 grams of freeze dried strawberries to a spice grinder, coffee grinder, or high-speed blend and process until it forms a fine powder. Sift the powder through a fine mesh sieve and discard any solid pieces. Measure 5 grams to use in this recipe.
It’s helpful to add the almond flour and powdered sugar to a food processor and pulse several times before sifting.
Knowing when the batter is finished being mixed is a real art, and can be tricky! A lot of people say it should flow like lava. A good test is to see if you the batter falls off the spatula in ribbons to make a figure 8 shape.