In a bowl, whisk all ingredients together to combine, except jam. Press dough together into a ball, wrap tightly, and chill in fridge 30 minutes to 1 hour.
Preheat oven to 350°F, with rack set in the center. Line a baking sheet with parchment paper.
Shape dough into small 1-inch balls. Roll each ball in granulated sugar to coat. Place on a parchment-lined cookie sheet.
Lightly press the center of each dough ball with your thumb to create a well.
Stir jam so that it's easy to pour into each cookie.
Add ¼ teaspoon of jam in the center of each cookie.
Bake 7 to 9 minutes, until just set on the outside but still very soft. Do not over bake.
Cool for 5 minutes on cookie sheet, and then transfer to wire rack to finish cooling.
Notes
Keep cookies in airtight container at room temp to preserve softness.