1. Prepare a sheet pan with parchment paper. For evenly sized cookies, trace small circles onto the parchment about 1 inch apart. I used an inverted shot glass, about 2" in diameter. Turn parchment over.
2. In food processor, pulse almond meal a few times to make it as fine as possible. Sift with powdered sugar into a large bowl. Make a well in the almond flour mixture and add 2 of the egg whites; combine with a spatula.
3. Place the other 3 egg whites into the bowl of a stand mixer fitted with the whisk attachment.
4. Combine the granulated sugar and water in a small saucepan and heat over medium-high. Use a candy thermometer to check the temperature of the syrup. Once it nears 200 F, start whisking the egg whites on medium speed. You want them to form soft peaks. If they get to soft peaks before your syrup is ready, turn mixer to low to keep whites moving.
5. Once syrup has reached soft ball stage (around 240 F), remove from heat. Allow to cool just enough that bubbles subside, then slowly drizzle hot syrup into egg whites with speed on medium-low.
6. Increase speed slightly and continue to whip a few minutes, until eggs form glossy, stiff peaks and cool a bit.
7. Fold about a third of this meringue into the almond meal mixture with a spatula, incorporating fully.
8. Continue to add meringue a little at a time until batter is at "ribbon" stage - it will fold over on itself, leaving a ribbon that disappears after a few seconds. You may not need all the meringue.
9. Scoop batter into a piping bag with a straight tip and pipe onto your parchment template.
10. Preheat oven to 350 F and allow piped cookies to dry slightly while your oven warms.
11. Bake until shell forms on top of macarons and a "foot" appears on the bottom - about 10-13 minutes. You should be able to gently lift the cookies off the parchment as soon as they are baked. Allow to cool completely.
1. Place sugar in a heavy-bottomed saucepan. Add just enough water to saturate sugar and blend lightly. Place over medium-high heat on the stove.
2. Add egg whites to clean stand mixer fitted with the whisk attachment. Begin whipping eggs once your syrup reaches around 200 F.
3. Once egg whites reach soft peaks and syrup reaches soft ball stage (around 240 F), remove syrup from heat. Allow bubbles to subside, then slowly drizzle hot syrup into eggs, whisking on medium speed.
4. Continue to whip a few minutes, until mixture has cooled slightly and has glossy, stiff peaks.
5. Begin adding soft butter, about a tablespoon at a time, until incorporated. Mixture may separate a bit, but it will come back together. Continue whisking until smooth.
6. Add vanilla and scraped vanilla bean.
1. Flip half of cooled macarons over and pipe buttercream on the bottoms, leaving a little space around the edges.
2. Sandwich with remaining macarons, pressing lightly to adhere buttercream.
3. Chill in refrigerator for at least an hour before serving.
Macarons will develop more flavor and chewiness as they sit. They will be even better the next day, so this is a great recipe to make ahead. Store in fridge.