For the Macaron Shells:
- 200 grams Powdered Sugar
- 100 grams Almond Flour
- 3 large Egg Whites, room temperature (120 g)
- 1/8 teaspoon Salt
- 40 grams Granulated Sugar
- zest from 1 1/2 Lemon
- 1-2 drops Yellow Food Coloring, (optional)
For the Lemon Rhubarb Buttercream:
- 1/2 cup Unsalted Butter, room temperature (1 stick)
- 3 cups Powdered Sugar, For the Lemon Rhubarb Buttercream
- 3 tablespoons Lemon Juice
- 3 tablespoons Rhubarb Jam
- 1/4 teaspoon Salt
- 1/3 cup Rhubarb Jam
- Add the powdered sugar and almond flour to a food processor and process for about one minute, or until the mixture is well blended and the almond flour is ground down to a fine powder. Sift the mixture into a bowl, discarding any pieces that don’t go through the sift. Set aside.
- Wash and completely dry your stand mixing bowl and whisk attachment. Briefly rub down both with lemon juice to ensure there is no fat or oily residue on the equipment. Add the egg whites and begin to whip on medium-low for about a minute.
- Add the pinch of salt when the egg whites get foamy and bring up the speed up to medium-high until the eggs reach soft peaks – this is when the meringue makes deep curls when you take out your whisk and point the whisk upward. This should take about 3 – 5 minutes.
- Add the granulated sugar once it reaches soft peaks and beat for about 2 minutes longer, or just as it is about to reach stiff peaks (stiff peaks happen when the meringue points straight up and does not curve when the whisk is pointed upward).
- Turn off the mixer and pour in the almond four mixture, lemon zest, and food coloring. Begin to mix everything together with a rubber spatula. At first it will seem as though it won’t work, but it will slowly come together.
- Scrape the bottom and sides of the bowl, folding the mixture onto itself. As you do this, also pull up some of the batter into the air to see if it drizzles down in a ribbon. Once it does this, check how long it takes for the ribbon to incorporate back into the batter. It should slowly flow back into the batter like magma. If the ribbon dissolves back into the batter within second, it is over mixed and will not hold a good shape. If it doesn’t ribbon, keep mixing otherwise you will end up with cracked, lumpy cookies.
- As soon as you reach the desired consistency, immediately stop mixing and set the batter aside uncovered for 30 minutes.
- While the batter rests, preheat the oven to 325°F.
- Line two baking sheets with Silpat macaron mats and fit a piping bag with a round piping tip. I do not recommend not using a tip as you will not have as much control.
- Fill the piping bag with the macaron batter and begin to pipe the batter, using the guides on the mat. You want to fill in the circles on the mats. For smaller macarons, you can pipe them so they are just under the black lines, for larger macarons, you can pipe until the black lines are fully covered.
- Once the macarons are piped, tap the baking sheets on your counter two or three times to remove air bubbles. Take a tooth pick to pop any small bubbles you may find.
- Leave the macarons to rest for at least 45 – 60 minutes.
- Bake the macarons one baking sheet at a time on the middle rack (do not place the second sheet in a lower or upper rack, they must be baked one at a time in the middle rack) for five minutes, then turn the baking sheet 180 degrees and bake for another 5 minutes.
- Remove the baking sheet and bake the other batch of macarons. Allow the baked macarons to cool on the baking sheet for about 5 minutes before transferring to a wire rack to cool completely.
- Make the buttercream. Beat the butter until it is smooth and cream. Add the powdered sugar one cup at a time, mixing each cup in fully before adding in more. Add in the lemon juice, rhubarb jam, and salt and mix until the frosting is smooth.
- Assemble the macarons. Turn the macaron shells upside down and pipe circles on half the shells. Add a dollop of rhubarb jam into the centers of the circles and top with the remaining shells.
- For the best results, freeze the finished macarons overnight before serving, but this is not required. Store in an airtight container for up to a week.