Cream together ½ cup of softened unsalted butter and ¾ cup of sugar until light and fluffy.

Add in 1 large egg and 1 teaspoon of vanilla extract, mixing until fully incorporated.

Gradually add in 1.5 cups of flour, 1 teaspoon baking powder, ¼ teaspoon baking soda, ¾ teaspoon cornstarch, and ½ teaspoon salt, mixing just until combined.

Cover the bowl with plastic wrap and refrigerate for about 2 hours.

Prepare the cream cheese filling by mixing 2.5 oz of cream cheese, a couple of tablespoons of sugar, and blueberry jam until smooth.

After chilling, take the dough out and scoop out a heaping tablespoon, flatten it, and place 1 teaspoon of cream cheese filling in the center.

Fold edges over the filling, roll into a ball, and place on the prepared baking sheet.

Bake at 350°F (175°C) for approximately 20 minutes.

Let cool for 5 minutes on the baking sheet before transferring to a wire rack.