Before you begin

1. Begin by aging your egg whites. Separate the whites from the yolks into a small glass bowl. Cover the whites with plastic wrap and store in the fridge for 24 hours up to 4 days, this helps diminish the moisture content while maintaining the protein bonds that are needed for the shells to form. Before using the egg whites allow them to come to room temperature.
2. This extensively informative Macaron guide from Food Nouveau goes into more depth about the importance of aged eggs, among everything else Macaron related (it's a brilliant post).
3. Finely zest a grapefruit and allow the zest to dry out for at least 2 hours before incorporating it into the meringue, you want it to be dry so the moisture doesn't affect the way the other ingredients come together.
4. It helped me immensely to draw 1"-1.25" guide circles lightly on the backside of the parchment paper in pencil. Be sure to leave at least 1"-2" of space between the circles.
5. I found grinding my own blanched almonds to work better than almond meal, however I did not try almond flour. They provided a consistent, smooth and clean texture without flecks of almond skin.
6. For the meringue I used caster sugar, a superfine sugar that melts quickly. I did not try using regular granulated sugar.

Grapefruit Macaron Shells

1. Line 2-3 baking sheets with prepared parchment paper.
2. Using a food processor, grind the almonds for about 1-2 minutes until evenly and finely ground, scraping down the sides of the food processor at least once. Do not over process or you'll end up with almond butter.
3. Add the sifted powdered sugar to the food processor and grind together for another 1-2 minutes until evenly combined. Sift the powdered sugar/almond mixture through a fine mesh sieve into a mixing bowl to eliminate any chunks, (this is a very important step).
4. Using a stand mixer (or a hand mixer), beat the egg whites on medium-high speed for 2 minutes until they start to foam and get frothy. Slowly add the caster sugar one tablespoon at a time, while whipping, until fully incorporated.
5. Continue to beat the egg white/sugar mixture until glossy and stiff peaks form. They should be firm and stand on their own, when the bowl is turned upside down they should stick to the bottom of the the bowl and shouldn't slide around. Quickly add the grapefruit zest and food coloring during the last moments of the stiffening process. Be careful to not overbeat the meringue, it should remain stiff and light.
6. Add half of the sifted almond mixture, gently folding it into the meringue using a spatula. Carefully lift the meringue from the bottom and up around the sides, toward the middle, being careful to not over mix the meringue. You want it to remain airy. Only folding 3-4 times, if possible. Once the first half of the almond mixture is incorporated, add the second half and carefully repeat the folding motion until just incorporated.
7. Authoritatively mix by hand about 10 rotations until the consistency is that of molten lava (because we all know just what that looks like, right?). But really, you want it to be smooth and shiny but still sturdy, not runny. It is better to undermix here than overmix. If you feel like you are overmixing, stop!
8. Pour the batter into a pastry bag fitted with a 0.5-inch tip. On your prepared baking sheets, pipe out 1-1 1/4" rounds within the circles that you drew on the backside of the parchment paper. Continue until you have used all of the macaron batter.
9. Forcefully rap the cookie sheets on the counter a few times to get rid of air bubbles and smooth out the tops of the macarons. Now allow them to rest on the baking sheets at room temperature for at least 30-40 minutes. A thin and tacky film should form during the resting period and if you gently touch with your finger the batter should not stick. 15-20 minutes into the resting period preheat your oven to 300°.
10. Just before baking sprinkle half of the shells lightly with coarse sea salt.
11. Bake one sheet at a time for about 15-18 minutes, rotating halfway through. The macarons are done when they are baked all the way through and the shells just start to harden. If you underbake them, the interior will come out mushy but if you overbake them they will start to brown in the oven and get crunchy. Watch them carefully and gently touch the top to test, they should feel firm but not hard and your finger shouldn't depress into them.
12. Allow macarons to cool completely on the baking sheets on wire racks. If you try to remove them from the parchment before they have fully cooled the bases may tear. Once they have fully cooled they should pop right off the parchment.

Grapefruit Gin Buttercream

1. Whip the butter on medium-high speed of an electric mixer using the whisk attachment for a few minutes minutes. Reduce the speed to medium-low, and gradually add the powdered sugar, mixing and scraping the sides of the bowl until all is incorporated.
2. While mixing on a medium speed, add the grapefruit juice and gin until incorporated and fluffy. If the frosting appears a bit too soft and thin, add some additional powdered sugar, one spoonful at a time until desired consistency is reached. Add a few drops of pink or red food coloring and blend until you are happy with the color.
3. Transfer the buttercream to a piping bag with a 1/4" tip attached and pipe the filling on the bottom macaron halves (the unsalted shells). Do not pipe all the way to the edge as the filling will spread when you add the tops. To assemble, gently press the salted tops onto the filled bottoms and twist slightly in opposing directions as you sandwich them together. This will lock the frosting in place and keep the cookies from separating.
4. You've done it, Bien fait!