Ingredients:
1/2 cup unsalted butter, softened
2 1/2 oz cream cheese, softened
3/4 cup sugar
1 egg
1 1/2 tsp vanilla extract
1 1/2 cups all-purpose flour
1 tsp cornstarch
3/4 tsp baking powder
1/4 tsp salt
4 oz white chocolate, chopped into small chunks
3/4 cup fresh blueberries
3 tbsp blueberry jam
1 tbsp powdered sugar