Step 1

Adjust oven rack to middle position and preheat to 350°F.

Step 2

Line two cookie sheets with baking paper.

Step 3

Fit a large piping bag with a 1/2-inch round tip. Roll the bag open and stand upright in a tall glass or jar so it can be filled hands-free.

Step 4

Separate the eggs, place the yolks in a large bowl and the whites in a stand mixer fitted with a whisk attachment.

Step 5

Using a hand mixer, whip the egg yolks with half the sugar, until pale and fluffy.

Step 6

Beat in vanilla extract.

Step 7

Fold in the lemon zest (optional) using the silicone spatula.

Step 8

Whip the egg whites on medium-high speed, until fluffy. Once light and fluffy, slowly add the rest of the sugar while continuing whipping. Whip until stiff peaks form. This is crucial as if the foam is unable to hold soft peaks, the lady fingers will spread flat in the oven!

Step 9

Using a silicone spatula, gently fold in the whipped whites into the yolk fluff, taking care not to deflate all of the incorporated air.

Step 10

Mix flour with cornstarch and salt using a small whisk.

Step 11

Add the flour mix slowly, folding gently with a spatula to combine in a lump free batter.

Step 12

Transfer to the piping bag, twist to close, and pipe fingers of about 3" x 1", leaving 1" between each one. Hold the bag at an angle when pipping and firmly lift the bag straight up when finishing pipping.

Step 13

Dust the cookies with powdered sugar and bake until puffed and a little golden, 12 to 15 minutes.

Step 14

Bake the second tray in a similar way.

Step 15

Cool the cookies completely in the tray, at room temperature.

Step 16

Transfer to an airtight container, if not used immediately as they'll begin softening in the air.

Step 17

Use immediately or store in an airtight container, at room temperature for up to 3 weeks.