Put the butter and sugar in a mixer bowl. Beat on medium speed for about 2 minutes, stopping once to scrape the bowl. Continue beating until the mixture is light and fluffy.
1 cup butter, 3/4 cup granulated sugar
Add the egg and vanilla to the mixer bowl and beat again for 1 minute.
1 egg, 1 teaspoon vanilla
In a separate bowl combine the flour, baking soda and salt and stir to mix. Then slowly add the flour mixture to the butter mixture and stir until just combined.
2 1/2 cups all purpose flour, 1/4 teaspoon baking soda, 1/4 teaspoon salt
Take the dough out of the mixer and wrap it in plastic wrap. Refrigerate the dough for at least one hour or as much as 24 hours.
When you are ready to bake the cookies preheat the oven to 350 F. Put parchment paper or silicone baking mats on your baking sheets.
Roll the dough into 1 inch balls and put them on the cookie sheets, leaving space between them. Use your thumb or a rounded teaspoon to make a well in the center of each cookie.
Use a spoon to fill each well with your desired flavor of jam, making sure not to overfill the cookies.
1/2 cup jam - apricot
Bake the cookies in the preheated oven for about 15 minutes, until they are just starting to turn golden brown.
Let the cookies cool on the cookie sheet for 5 minutes, then take them off and put them on wire racks.
Once they are completely cool sprinkle them with powdered sugar if desired.