Macaron Shells

• Preheat your oven to 300 degrees Fahrenheit (150 degrees Celsius) and prepare a large baking sheet by lining it with parchment paper or a silicone mat. If using a silicone mat, wipe the mat down with white vinegar.
• Sift the almond flour and powdered sugar together into a bowl. For extra smooth macaron shells, you can transfer the dry mixture to a food processor and pulse together to remove any lumps, then sift the dry ingredients again. If required, repeat this process until the mixture is lump-free.
  140 grams almond flour, 125 grams powdered sugar
• Whip the room temperature egg whites in a stand mixer with a whisk attachment on low speed until foamy, then add the cream of tartar.
  100 grams egg whites, ¼ teaspoon cream of tartar
• Continue to whip the egg white mixture on medium speed until soft peaks form and then slowly add the sugar to the egg whites. Keep the mixer running while adding the sugar.
  100 grams granulated sugar
• Once the sugar has been incorporated, add the blueberry flavoring and a few drops of purple food coloring (you can also use a combination of blue food coloring and red food coloring to make a shade of purple that you like).
  ½ teaspoon blueberry flavoring, gel food coloring
• Continue whipping the mix on medium speed until stiff peaks have formed. This will take approximately 10-15 minutes and you'll know you've reached stiff peaks when the meringue stands straight up on the whisk and the tip doesn't flop over.
• Once stiff peaks have formed, add half of the dry ingredient mix to the bowl and fold gently into the meringue using a silicone spatula. Repeat until all of the dry ingredients have been incorporated.
• Continue to fold the mixture until it has reached a lava-like consistency. At this point, transfer the batter to a pastry bag with a large round tip (or use a piping bag with the end cut off) and pipe the mixture onto the prepared baking trays.
• Tap the tray on the countertop a couple of times to remove any air bubbles then allow to rest for 30 to 45 minutes, or until a skin has formed.
• Bake at 300 degrees Fahrenheit (150 degrees Celsius) for 15 to 18 minutes then remove from the oven. Allow the macaron shells to cool on the tray completely.
• While the macaron shells are cooling, make the American buttercream. To make the vanilla American buttercream, beat the butter on medium speed for 30 seconds using a electric mixer with a paddle attachment.
  ⅓ cup unsalted butter
• At a low speed, add the vanilla and salt, and then slowly add the powdered sugar to the mix, alternating with splashes of milk or cream. The buttercream should be a reasonably thick consistency to be able to create a dam to contain the vanilla blueberry jam, so don't add too much liquid.
  ⅛ teaspoon salt, 1 teaspoon vanilla extract, 1½ cups powdered sugar, 1 tablespoon heavy cream
• Once the buttercream is done, spoon it into a large piping bag and it's ready to use to fill the blueberry macarons.
• If using homemade blueberry filling, prepare it by following this recipe for vanilla blueberry jam.
  12 ounces blueberries, ½ cup granulated sugar, 1 tablespoon lemon juice, ½ teaspoon lemon zest, ½ teaspoon vanilla extract
• Once the buttercream and blueberry filling is prepared, assemble the macarons. To assemble the macarons, begin by matching up similar-sized macaron shells in pairs.
• Pipe a ring of vanilla American buttercream around the inside of one macaron shell, leaving a small gap between the buttercream and the edge of the shell. Fill the center of the ring with a small spoonful of blueberry jam.
• Gently press the second macaron shell on top to create a sandwich. Repeat the process until all the macaron shells are assembled.
• Place the assembled macarons in an airtight container and refrigerate for at least 24 hours to allow the flavors to meld and the macarons to soften slightly.
• Remove the blueberry macarons from the refrigerator and let them come to room temperature before serving.