The Swiss meringue buttercream filling is spiked with a reduction of fresh lemon juice and zest which adds zip and balances the sweetness of the macaron shells.
I made them just like my recent batch of Lime Macarons except that I used yellow food coloring instead of green and lemons instead of limes.
Here's the recipe:
180g ground almonds, sifted
270g powdered sugar, sifted
150g egg whites, aged 2 to 4 days in the fridge and then brought to room temperature
100g granulated sugar
yellow food coloring
Line five heavy baking sheets with good quality parchment paper and set aside. Also, set aside two pastry bags for the piping of the macarons.
Sift together your ground almonds with the powdered sugar and set aside.
Whisk the egg whites (at room temperature) to glossy firm peaks adding the granulated sugar gradually in four parts. Towards the end of mixing, add the food coloring.
Incorporate the dry ingredients into the beaten egg whites using a large rubber scraper. Mix well.
Fold the mixture with the rubber scraper by pulling down the sides and flipping the mixture over. Do this until you have a smooth mixture that falls like a “ribbon” off the scraper.
Transfer the mixture into the two piping bags. Use rubber bands to close the piping bags. Clip the tip of the bags, one at a time, and pipe quarter-sized rounds, leaving 1-inch of space between each because they spread as they set.
Leave to set for about 30 minutes or until the top has formed a crust and is not sticky to the touch.
While they are setting, preheat the oven to 325 degrees. A convection oven is preferable.
Bake one sheet at a time in the center of the oven for about 12 minutes or until the cookie is firm, matte and doesn't wobble when touched.
Leave on the baking tray until cool then lift them all off the parchment carefully. You may need to use a thin knife to help lift them off.
Sort into pairs and fill with Lemon Buttercream
zest of two lemons
1/3 cup fresh lemon juice
3 tablespoons sugar
3 large egg whites
1/2 cup granulated sugar
1/8 teaspoon cream of tartar
1 cup unsalted butter, room temperature
pinch of fine sea salt
yellow food coloring, optional
Mix together the zest, 3 tablespoons of sugar and lemon juice and add it to a small saucepan. Over medium heat, heat the mixture until it comes to a boil, watching it and stirring it constantly. Simmer the mixture for about 5 minutes until it's reduced and begins to caramelize on the edges. The zest will change color to a darker yellow.
Remove the mixture from the stove and transfer it to small bowl to cool. Let it cool completely.
Place the whites in a clean mixing bowl. Whisk in sugar and cream of tartar.
Place bowl over a double boiler on medium heat, stir frequently until the mixture is very hot (120 to 130 degrees Fahrenheit).
Move to mixer and whip whites on high for 2 to 3 minutes; turn down to medium low until cool (use the bowl as your guide).
In a separate bowl with a wooden spoon, stir butter to soften.
With mixer on medium/high speed, add the butter one tablespoon at a time, adding the next tablespoon just as the previous one is blended in. Once all the butter incorporated, add in the salt and cooled lemon mixture and whip on high speed until fluffy. If desired add a touch of yellow food coloring.