Preheat your oven to 350 degrees F.

Line a baking sheet with parchment paper and set aside.

Using a stand mixer cream together the butter and sugar until light and fluffy, I just use the paddle attachment. You will have to scrape the sides of the bowl a few times.

Add the egg yolk and vanilla, mix well.

In a separate bowl whisk together the flour and salt.

Add the flour mixture to the butter mixture and combine.

Roll the cookie dough into 1 inch smooth balls and place them on the prepared baking sheet about 2 inches apart. Note: this recipe makes 24 cookies, so bake them in 2 separate batches, 12 cookies per baking sheet.

Using your thumb or finger, make an indent in the centre of the ball (circular to hold the jam).

Use a small spoon to add about a 1/4 to 1/2 a tsp of jam to the indent in each cookie.

Bake for 12 - 14 minutes. The bottom edges of the cookies should be very light golden brown.

Cool on a wire rack.