Preheat the oven to 180°C and position a rack in the center. Set aside your springform pan since there's no reason to grease them with all the butter in the recipe.
In a large bowl with an electric mixer cream the butter and sugar.
Add the almond extract and egg and mix it well.
Beat in the flour until it's well incorporated and it forms a heavy thick dough.
Press the dough evenly into the form with your fingers. Sprinkle a generous layer of almonds over (we ommited this) and press them down lightly.
Whisk together the egg white and water then brush it over the almond layer with a pastry brush.
Bake them for about 20 – 30 minutes depending on the depth of your dough.
You'll know it's done when it rise slightly in the center and the edges turn light golden brown.
Let it cool for at least 10 – 15 minutes in the form.
Run a small paring knife along the edges to release the seal of the crisp egg white then turn it upside down.