Preheat the oven to 350°.
Mix flour, corn starch, salt, and baking powder together in one bowl.
Mix butter, sugar, egg, and vanilla into one bowl using a mixer.
Add the flour, corn starch, salt and baking powder into the second bowl and mix with a mixer.
Add white chocolate chips and blueberries.
In a separate bowl, mix cream cheese, powdered sugar and vanilla to make a cream cheese filling.
Take a small ball of the dough and make a thumb print in the center.
Add a small amount of cream cheese filling and blueberry jam into the center.
Close the cookie around the filling then place on a cookie sheet.
Bake for 16-18 minutes.