Preheat the oven to 350 degrees F. With an electric mixer, cream the butter, sugar, and vanilla extract, for 3-5 minutes, until light and fluffy. Scrape the bowl with a spatula. Turn the mixer on low and add the salt. Add the flour a little at a time, until it is just combined.
Line several cookie sheets with parchment paper. Roll the dough into 1-ounce balls, about 1 ½ tablespoons per ball.
Place the dough balls on the cookie sheets about 2 inches apart. Press the center of each ball with your thumb to create a cavity. Hold the sides of the cookie with the other hand to help keep the dough from cracking. Press any cracks back into place.
Fill each indentation with ¼-½ teaspoon of raspberry preserves. (Any more and they will overflow while baking.) Bake for 15-20 minutes, until the edges are just barely golden.
Remove the cookies from the oven and cool completely before moving. Then sprinkle with powdered sugar and serve!
