Vanilla macarons with vanilla buttercream (Thomas Keller, Bouchon)

Trace two-inch circles on parchment about one inch apart, flip the parchment and lay it on the baking sheets.

Whisk the almond flour into the powdered sugar.

Split the vanilla beans and scrape out the seeds.

Whip room-temperature egg whites on high until they begin to hold their shape.

Gradually add the granulated sugar on high until fluffy, add the cream of tartar, and beat to stiff peaks.

If over-whipped, whisk in a little extra egg white by hand.

Fold in half of the almond-sugar mix carefully, then the vanilla seeds, then the rest of the almond-sugar mix; it looks dry at first and combines with folding.

Fill a piping bag with a half-inch plain tip; hold it upright half an inch above the centre of each circle and pipe without moving the tip, stopping short of the full circle since the batter spreads.

Tap the bottom of the sheet to even out the batter, and pop surface air bubbles with a toothpick.

Let the piped shells dry for one to two hours.

Bake at 325F with one tray on the top rack and one on the bottom for 10 minutes.

Switch racks and rotate the pans, then bake another 10 minutes.

Cool the shells, then peel them off the parchment.

For the buttercream, put the water and sugar in a saucepan and simmer until the sugar dissolves.

Cook the syrup to 248F, between soft ball and firm ball, brushing the sides of the pan with a wet pastry brush so no sugar sticks.

Whisk the four eggs in the mixer on high for two minutes.

Reduce the speed and pour the syrup in without hitting the whisk; mix on medium high until cooled to room temperature.

Add the softened butter in chunks, a little at a time; if the mixture separates keep mixing until it recombines.

Mix in the vanilla seeds.

Pair matching shells, put about a tablespoon of buttercream on one, and press the other on gently until the filling spreads near the edge.

Store in an airtight container at room temperature for a day or two, or freeze for up to two weeks.