Snickerdoodle cookies with a folded-in meringue

Separate the egg; white into the mixing bowl, yolk set aside.

Add a tiny shake of cream of tartar to the white and beat with electric beaters to soft peaks, about 90 seconds.

Beat in the 50 g sugar; keep beating if the foam collapses until it comes back. Stiff peaks are not needed. Set the meringue aside.

Cream the shortening and the 100 g sugar for a few minutes until very fluffy, like frosting.

Beat in the egg yolk, then the vanilla, salt, the teaspoon of cream of tartar and the baking soda.

Fold in all the meringue.

Mix in a cup of flour, then more, up to about 160 g total, until the dough is just solid enough to roll into balls.

Roll into balls bigger than a golf ball.

Roll each ball in a coating of one part cinnamon to two parts sugar until very well coated.

Flatten slightly into tall pucks.

Bake, convection if available, at 400F / 200C for 3 to 4 minutes, then turn down to 350F / 180C.

Bake at 350F / 180C until spread and cracked and the wet dough in the cracks just starts to dry; lean toward underbaking. About 12 minutes in all.