Mix butter and sugar (white and brown) in bowl until creamy.Add 1 egg at the time, mixing well after each addition, then add vanilla.
Combine flour, salt and ground almonds in a bowl and add them to the butter mixture gradually until the dough it is hard enough to work with. If it is sticky, add the remaining ½ cup flour, then refrigerate it for 1 hr.
After refrigeration, roll out the dough on a lightly floured surface to ⅛ inch (3 - 4 mm) thickness.
Cut out circles or Christmas tree shape cookies and half of them cut in the middle with a circle cutter.
Arrange them 1 inch apart in a greased cookie sheet and bake them for 12 minutes at 350F or 175 C degrees.
Let them cool down on the cookie sheet for about 5 minutes then you can spread them with jam . dust cookies with cut out centers with icing sugar and place on top of jam.
Recipe by gabriela cuisine at http://gabrielacuisine.ro/biscuiti-linzer/