I always use Kosher salt in my kitchen! If using table salt, start with half the amount and adjust to taste, as it is much "saltier" by volume.
Instructions
In a mixing bowl, cream together the softened butter, ⅓ cup of granulated sugar, and brown sugar until light and fluffy. Add in the egg yolk, both extracts and mix until well combined.
In a separate bowl, whisk together the flour, salt, and cornstarch. Gradually add to the wet ingredients, stirring until fully incorporated.
Scoop heaping tablespoons of the dough onto a parchment lined baking sheet. Roll each dough ball in the additional ⅓ cup of granulated sugar, then use the back of a teaspoon to press an indent into each cookie. Place the baking sheet into the freezer for 30 minutes.
Preheat an oven to 375°F. Remove the cookies from the freezer and fill each indent with ½ teaspoon of raspberry jam or enough to fill the indent. Bake for 11-12 minutes or until lightly browned around the edges. Enjoy!