In a cast-iron skillet, toast the seeds until they are the color of an unpopped kernel of popcorn, about 10 minutes. Remove from pan and set aside.

Preheat oven to 375°F. Line two baking sheets with parchment or silicone mats.

Sift together, flour, sugars, salt, and baking powder. Sift again. And again.

In a stand mixer, beat egg white until it holds medium-hard peaks.

Add the dry ingredients in four additions, mixing thoroughly before adding more.

Drop in the butter pieces and beat, scraping down the sides of the bowl as needed, until completely incorporated and the batter is shiny, about 3 minutes.

Mix in vanilla and toasted seeds.

Scrape dough into a piping bag, or a Zip-Loc style bag with a tiny bit of corner removed.

Pipe 1/4 tsp dabs of dough onto baking sheets 1 to 2 inches apart.

Bake for 5 minutes or until cookies have risen, collapsed, and browned.

Cool on sheets for 5 minutes, then transfer to a airtight tin.