In a large bowl, cream together butter and ½ cup of sugar. Add egg and vanilla, mix to combine.

In a separate bowl, whisk together flour and salt. With the mixer on low, gradually add the flour mixture to the butter mixture. Beat until completely combined. Cover and chill for 30 minutes.

Preheat oven to 350 degrees F. Line two baking sheets with parchment or silicone mats. Set aside.

Place remaining ¼ cup of granulated sugar in a small dish.

Scoop the chilled dough into heaping tablespoons (I like to use a cookie scoop for this step) and roll into balls. Roll the dough balls in the granulated sugar. Place on prepared baking sheets.

Use your thumb or finger to create an indent in the center of each ball. Spoon about ¼ - ½ teaspoon of jam into the center of each cookie. Place the baking sheets back in the refrigerator or freezer to chill for about 10 more minutes.

Bake at 350 degrees F for 12-14 minutes, or until the cookies are set and golden brown on the bottom. Cool on the baking sheets for about 5-10 minutes before transferring to wire racks to cool completely.