Plan ahead - Take butter out of the refrigerator and keep in mind that the dough has to be chilled for 30 minutes.
Preheat your oven to 350 degrees F/175 degrees C.
In your stand mixer fitted with the paddle attachment, cream together the butter and both the sugars until they are light and creamy and then add the vanilla.
In a separate mixing bowl, sift together the flour and salt.
With the mixer running on low speed, add the flour mixture to the creamed butter and sugar.
Mix until the dough comes together. you can add upto a tablespoon of milk if need be.
Cut a piece of plastic wrap big enough to hold the dough and lay it on your kitchen counter. Dump the dough on the plastic wrap and roll together into a flat disk. Wrap in plastic completely and chill for 30 minutes.
After 30 minutes, take the dough out and break about a tablespoon of dough from the disc and roll it into approximately 1 inch balls.
Place the balls on an ungreased cookie sheet and press a light indentation into the top of each using a round ½ tablespoon measure (see tools used below). Drop ¼ teaspoon of your choice of jam into each indentation.
Bake for 20 to 25 minutes, until the cookies are golden brown. Cool for 10 minutes and serve.