First make the filling-

In a medium size bowl with an electric mix together cream cheese, and sugar until well blended. Add in salt, vanilla, egg yolk and sour cream, continue mixing until everything is evenly mixed. Cover the bowl with plastic wrap and place in the refrigerator for at least 30 minutes.

To make the cookies-

Preheat the oven to 350 and line a baking sheet with parchment paper.

In a medium bowl whisk flour, and salt, mix until well incorporated.

In a large bowl with an electric mixer or the bowl of a stand mixer fitted with a paddle attachment cream together butter and sugar.

Add in egg yolk and vanilla and continue mixing on medium speed until well incorporated.

Add the dry ingredients in gradually, mixing after each addition, until it is all added and a soft dough forms.

Scoop out cookie dough in tablespoon size scoops and roll into balls.

Place balls of dough onto the prepared cookie sheet.

Using the handle end of a wooden spoon, your finger, or another small round object press a hole in the center of each ball.

Bake for 10 minutes.

Remove from the oven, gently press in the center of each cookie again with a wooden spoon (not your finger) and fill with the cream cheese filling.

Place cookies back in the oven and bake 10-12 minutes or until the filling is set and cookie is golden brown

Allow to cool on the baking sheet for 2-3 minutes before removing to a wire rack to cool completely .

Store in an airtight container.