Strawberry Macarons

Ingredients
For the shells

• 260 grams confectioners' sugar, about 2 cups plus 2 tablespoons - SEE NOTE 1
• 150 grams Bob's Red Mill Almond Flour, about 1 2/3 cups
• 10 g strawberry powder2, about 2 tablespoons
• 150 grams egg whites, about 4 large egg whites (at room temperature)
• 1/4 teaspoon cream of tartar
• 52 grams granulated sugar, about 1/4 cup
• 1T beet powder (1 - 2 drops red food coloring) optional

For the filling

• 100 g granulated sugar (1/2 C)
• 70 g egg whites, about 2 large egg whites
• 1/8 teaspoon salt
• 169 g unsalted butter, about 3/4 cup (cut into pieces at room temperature)
• 20 g strawberry powder, about 1/4 cup - SEE NOTE 2

Instructions
Make the shells

1. Set the oven rack to the lower third position. This is just below the center of the oven. Place an empty baking sheet on the rack and line 4 more baking sheets with silicone macaron mats. Preheat the oven to 300°F.
2. Using a fine-mesh sieve, sift the almond flour, confectioners sugar, beet powder, and strawberry powder into a large bowl. Repeat 2-4 times and discard any clumps. Don't force the clumps through the sieve!
3. In the bowl of a stand mixer fitted with the whisk attachment, whip the egg whites and cream of tartar on medium speed until foamy. Gradually add the granulated sugar. Turn the speed up to high and whip until soft peaks form. (Add 1-2 drops of food coloring if using and not beet powder)
4. Continue to whip on high speed until a thick, glossy meringue forms. Take extra care to not over whip.
5. Using a silicone spatula, fold half the almond mixture into the meringue until fully combined. It’s okay to be a little rough at the point. You want to knock some of the air out of the batter.
6. Add the remaining almond mixture and gently fold everything together. This is the part where the batter can go wrong. Overmixing or undermixing will cause issues with how the macarons bake up. After a couple of stirs, you’ll need to stop and check the consistency of the batter. Continue to do this until the batter is just right. (The batter should be shiny and flow like lava. You will be able to let the batter slide off the spatula as you draw a figure 8 and the batter won’t break. The figure 8 you just drew should rest on top of the batter in the bowl without sinking in and losing its shape.)
7. Transfer the batter to a large pastry bag fitted with a medium round piping tip. Be as gentle as you can with the process. Try not to overwork the batter.
8. Pipe 1 to 2-inch rounds onto the prepared baking sheets. Gently tap the baking sheet on the countertop to bring any air bubbles to the surface. Let the macarons sit for 30 to 60 minutes, until a dry skin forms on the surface. They should not feel sticky to the touch when going into the oven.
9. Bake one sheet at a time for about 15 to 18 minutes. The macarons are done when you can gently press on the shell and lightly rock your finger back and forth without it moving. If the top of the macaron is wiggly, it needs another minute or two to bake.
10. Cool the shells completely on the baking sheet set on a wire rack. Do not attempt to remove the shells from the silicone mat until they are completely cooled or they may stick and break off.
11. Sandwich two cookies together with strawberry buttercream filling. Store the filled macarons in the refrigerator for at least 1-3 days and bring them to room temperature just before serving. They taste the best this way.

Make the filling

1. Combine the sugar, egg whites, and salt in the bowl of a stand mixer. Set the bowl over a saucepan filled with 1 inch of barely simmering water. Whisk gently and continuously while heating the mixture. It should register 150°F on an instant-read thermometer. The sugar should be fully dissolved.
2. Transfer the bowl to the stand mixer and fit it with the whisk attachment. Beat on medium speed until the mixture is the consistency of shaving cream and cooled slightly, 1-2 minutes. (If the meringue is warm it will melt the butter.)
3. Gradually add the butter, 1 tablespoon at a time, until smooth and creamy. (Only add the next tablespoon of butter once the last one has been completely mixed in.)
4. Once all the butter is added, scrape down the sides of the bowl and mix on medium-high and beat until light and fluffy, about 30 seconds.
5. Add the strawberry powder and continue to mix on medium-high until incorporated.

Notes

1. Make sure the confectioners' sugar contains cornstarch. This ingredient will make all the difference in how the macarons turn out. (Can make confectioners' sugar from ground granulated sugar + 1T corn starch for 1 C confectioners;  For 1 C confectioners use 4oz (1/4C) granulated by volume)
2. You can purchase strawberry powder on amazon or you can purchase freeze-dried strawberries and grind them in a food processor.
3. If you don't have a silicone baking mat for macarons, you can use a 1.5-inch round cookie cutter and trace 20 circles onto sheets of parchment paper cut to fit the baking pans. Set another sheet of parchment paper over each template.
4. Make sure you double up on the baking sheet or the bottoms of the macarons will be too brown!
5. Read my posts on making macarons and swiss buttercream for more tips and techniques!

Make ahead tip

1. Macaron shells can be made up to 3 days in advance. Store in an airtight container and separate the shells with layers of parchment paper. Keep refrigerated until ready to use.
2. Once filled, store the macarons in an airtight container in the refrigerator for up to 3 days.
3. The filling can be made 1 day in advance. Keep refrigerated in an airtight container. Bring to room temperature and re-whip before using it.
4. The filling can also be frozen for up to 2 months. Thaw it in the refrigerator overnight then let it come to room temperature and re-whip before using.

From: https://www.bakedbyanintrovert.com/strawberry-macarons/