Heat your oven to 300°F. Line a baking sheet with parchment paper.

Add the egg white and cream of tartar to a mixing bowl. Use a hand mixer to beat the egg white until it's fluffy and holds soft peaks.

In a second bowl, whisk together the almond flour, sugar, and salt. Mix in the beaten egg whites to form a sticky dough -- it's ok if the eggs whites deflate while mixing.

Sprinkle the confectioner's sugar onto a cutting board or plate.

Divide the dough into 6 portons. Dampen your hands to eep the dough from sticking to them, then roll each piece of dough into a ball. Roll the ball over the confectioner's sugar to coat it lightly, then place it on the prepared baking sheet.

Press your thumb into the top of each cookie to create a divot. Fill each divot with 1/2 teaspoon of preserves.

Bake for 21-23 minutes, or until the tops of the cookies are firm and the bottoms are very lightly browned.