Heat the oven to 350°F and grease two baking sheets. Mix the butter until it is soft and add almost, but not all of, the suger. Keep mixing until the mixture is soft and mushy. Add the vanilla and then the egg yolks, one at a time, alternating with the flour. Keep mixing until the dough is soft, but not sticky. (If it's sticking, add some more flour.) Make the dough into a ball and put it into a bowl.

Divide the dough into 50 little balls about 1 inch wide. Roll the balls in the palm of your hand to make them round and then place an almond on top. Beat the egg white and smear a little bit on top of each cookie. Sprinkle with the reminaing sugar and put it on the baking sheet.

Cook for 20 minutes or until the cookies just start to turn golden brown. Take them off the baking sheet with a spatula and leave them to cool.

Serve : 50 cookies

Ready in : 40 minutes