Yield about 56 shells, or 28 assembled macarons
These colorful Strawberry Rhubarb Macarons burst with the juiciness of fresh strawberries and the tickling tartness of rhubarb.
For the rhubarb buttercream (see note)
For the macaron shells
At least 24 hours in advance, make the strawberry and rhubarb pâtes de fruits. Refrigerate until ready to use.
For the rhubarb buttercream: In a small saucepan, combine the rhubarb, water, and granulated sugar. Bring to a boil over medium heat and cook until the rhubarb breaks apart, about 5 minutes. Use a stick blender to puree the rhubarb mixture to a super smooth consistency. Transfer to a shallow bowl and refrigerate to cool completely.
Place the butter in the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl if using a hand mixer, and beat for a minute to soften. Add half the powdered sugar and beat on low speed to moisten the sugar, then increase the speed to incorporate fully. Add 1/4 cup (60 ml) of the cooled rhubarb puree and beat to incorporate fully. Incorporate the remaining powdered sugar. At this point, the buttercream should be fairly thick, so add more rhubarb buttercream to reach a creamy, but not too loose consistency (you will probably have a bit of puree leftover). Beat on medium speed until the buttercream is smooth and fluffy. Transfer to a pastry bag fitted with a small round tip and set aside until ready to assemble the macarons.
For the macaron shells:
*Return the egg whites to room temperature at least an hour before making the macarons shells.*
In the bowl of a food processor, add the powdered sugar and almond flour, and process until the mixture is thoroughly incorporated, 30 seconds to a minute. Sift the mixture through a fine-mesh strainer to make sure no lumps or bigger bits of almonds are left.
In the bowl of a stand mixer fitted with the whisk attachment, or in a large stainless steel mixing bowl if using a hand mixer, whisk the egg whites on medium/high speed until frothy. Add a tablespoon of the granulated sugar, continue whisking at medium-low speed, then add the remaining sugar slowly. Increase the speed medium-high and whisk until the egg whites are bright white and create stiff peaks. At low speed, mix in a few drops pink gel food coloring, to your liking.
Using a spatula, gently fold in the almond and sugar mixture into the meringue in 2 or 3 additions. Slide your spatula all the way to the bottom of the bowl and comes back up several times to make sure no pockets of dry ingredients remain.
Transfer the macaron batter in a pastry bag fitted with a ½-inch (1.25-cm) round tip. Pipe 1.5-inch (3.8-cm) rounds of batter, evenly spaced but still close to one another as they will not expand much.
Carefully slide the macaron templates off the baking sheets, if you used them. Lightly sprinkle strawberry-flavored sugar over the shells, if desired. Let the shells rest on the baking sheets for 20 to 30 minutes.
Preheat the oven to 275°F (135°C) with a rack in the middle position. Bake the macarons for 16 to 18 minutes, rotating the pan after 10 minutes.
Let the shells cool completely to room temperature before assembling them, about an hour.
To assemble the macarons: Take the pâtes de fruits out of the refrigerator. Pull the mixture out of the baking dish using the overhanging wax paper and set over a cutting board. Detail about 28 small, thin squares of pâtes de fruits: each piece should be about 0.4 inch (1 cm) square and 0.2 inch (0.5 cm) thick. Cut the rest of the pâtes de fruits into larger bite-sized cubes, and store in an airtight container in the refrigerator to enjoy later.
Pair same sized shells together and set side by side on a work surface. Pipe some buttercream over half of the shells, following the circumference of each shell to create a circle of buttercream. Fill each circle with a piece of pâte de fruit. Close the macarons, gently pressing the second shells over the filling.
Store the assembled macarons in an airtight container and refrigerate for one night before indulging.
Always bring these Strawberry Rhubard Macarons back to room temperature before serving.
NOTE: This recipe makes about twice the amount of frosting you need to fill the macarons. Use the remaining frosting to garnish a cake or cupcakes, or freeze it in an airtight container until you make a new batch of macaron shells. Simply defrost the buttercream by placing the container in the fridge overnight, or an hour at room temperature. Whisk vigorously to soften before using.
Recipe by Food Nouveau at https://foodnouveau.com/recipes/desserts/macarons/strawberry-rhubarb-macarons/