Step 1

Preheat oven to 350 degrees F.

Step 2

Distribute walnuts evenly across a sheet pan. Toast in oven for 10 minutes. Remove and allow to cool.

Step 3

Once walnuts are cool, add them to the bowl of a food processor and blend until the mixtures looks like very coarse sand, about 10 seconds.

Step 4

Lower oven temperature to 250 degrees F.

Step 5

In a large bowl, add the egg whites and with a stand mixer or handheld mixer, beat whites until soft peaks form. Add the sugar and continue to beat until stiff, shiny peaks form.

Step 6

With a rubber spatula, fold the vanilla extract, lemon zest and ground walnuts into the beaten egg whites.

Step 7

Line a sheet pan with a silcone baking mat or parchment paper. Place 20 spoonfuls of the batter, about 1 tablespoon each, onto the pan.

Step 8

Bake in oven for 1 hour and 10 minutes.

Step 9

Allow to fully cool. They will get crunchier as they cool.

Step 10

Store in an airtight container.