Place the butter, granulated sugar and brown sugar in the bowl of a mixer. Beat until light and fluffy, about 2-3 minutes.
Add the egg and vanilla extract, then beat for 1-2 minutes or until well combined.
Add the flour, baking soda and salt to the bowl. Beat until just blended.
Place the dough on a large sheet of plastic wrap and form it into a disk. Cover the dough completely with the plastic wrap, then refrigerate for at least one hour, or up to 3 days.
Remove the cookie dough from the refrigerator about 10 minutes before you plan to use it.
Preheat the oven to 375 degrees F.
Roll the dough into 1 inch balls, then coat each ball in granulated sugar.
Place the balls of dough 3 inches apart on 2 sheets pan lined with parchment paper or silicon baking mats.
Use your thumb, the back of a teaspoon, or the round end of a pestle to make an indentation in each cookie. Be gentle as you make each indentation so that the cookies don't crack.
Fill each cookie with 1/2 teaspoon of jam.
Place the trays of cookies in the freezer. Chill for 10-15 minutes or until cookies are firm.
Bake for 10-11 minutes or until light golden brown around the edges. Let sit for 5 minutes, then transfer to a rack and cool completely.