Using a mixer fitted with a whisk attachment, beat the butter on medium speed for about 3 to 5 minutes until the butter is light and fluffy. Mix in the sugar until well blended then add in the flour and continue mixing until the dough is formed. Wrap the dough with saran wrap and chill the dough for about 3 hours. Chilling the dough will prevent the cookies from spreading out too much when baked.
Preheat the oven to 375*F.
Use a small spoon to tear out small pieces of dough and use the palm of your hands to roll them out into small balls about the size of a hazelnut. Place them on a cookie sheet and chill them in the freezer for 30 minutes.
Line 3 cookie sheets with parchment paper. Place the cookies 2 inches apart on the prepared cookie sheets (cookies will spread). Bake one sheet at a time for 8 to 10 minutes or just until the cookies are firm and pale golden in colour. Keep the remaining cookie sheets chilled till ready to bake the next batch.
Spread the flat side of half the cookies with the jam and then top with remaining cookies to form a sandwich. Once you have paired them and formed little sandwich cookies, roll them in vanilla sugar to coat all over.
This recipe is adapted from a wonderful cookbook: Chocolate and Vanilla by Gale Gand