Line two sheet pans with parchment paper or silicone baking mats and set aside. (Make room in the refrigerator for the sheet pans or line a plate that will fit in the refrigerator with parchment paper).

Place butter, kosher salt, granulated and brown sugar in the bowl of a stand mixer or use a hand mixer and beat on medium-high until creamy, about 3 minutes. Scrape the bowl.

Then add the egg yolk and vanilla and mix on medium until well combined, about 1 minute.

Now scrape the bowl and slowly add the flour, mixing on low just until the dough comes together.

Place the dough balls on the prepared baking pan, spacing (or plate to fit in the refrigerator). Use the rounded back of a ½ or 1 teaspoon to press an indent into the cookie dough.

Spoon the blueberry preserves into each indent, filling it to the top.

Place the prepared cookie dough in the refrigerator to chill while the oven preheats to 350°F. (ideally 20 minutes of chill time)

Once the dough has chilled and the oven is ready, bake the cookies for 12-14 minutes or until the edges are barely golden brown.

Transfer to a cooling rack to cool while you make the cream cheese filling.

Add in the vanilla and powdered sugar and mix until a thick frosting is formed.

Move the frosting to a piping bag fitted with a round tip.

Once the cookies are cool, squeeze the filling into the blueberry preserves. If desired, use a small knife or toothpick to swirl the filling into the blueberries.