In the mixing bowl of a stand mixer fitted with the paddle attachment, add the butter and granulated sugar. Beat on a medium speed for two to three minutes or until the mixture is light and creamy.
1 cup unsalted butter, ⅔ cup granulated sugar
Add the vanilla extract and salt and beat until thoroughly combined.
1 teaspoon vanilla extract, ½ teaspoon kosher salt
Scrape down the sides of the mixing bowl and reduce to a low speed. Gradually add in the flour, scraping down the sides and bottom of the bowl as needed. The dough may not appear like it's coming together but give it a minute or two. You can also work the dough with your hands to make it come together quicker.
2 cups all-purpose flour
Roll the dough into a ball and wrap it in plastic wrap. Refrigerate for one hour.
Once the dough has chilled for an hour, preheat the oven to 350°F and line two baking sheets with parchment paper.
Place 1/3 cup of granulated sugar in a shallow bowl.
⅓ cup granulated sugar
Scoop one tablespoon of dough and roll into a ball. Coat each ball of dough by rolling in the bowl of sugar. Place the balls on the prepared baking sheets.
Make an indentation in the center of each cookie using your thumb. Fill with half a teaspoon of jam. Repeat until all cookies are filled.
¼ cup jam
Bake for 14 to 15 minutes or until the bottom edges just begin to brown. Let the cookies sit on the baking sheet for one additional minute before moving to a wire rack to cool.
Let cookies cool completely before storing in an airtight container.