1. Preheat oven to 350 degrees Fahrenheit.
2. Combine eggs, sugar, oil, lemon extract and milk, until well incorporated.
3. Mix flour, baking powder, cornstarch, salt and lemon zest. Mix together with wet ingredients until dough forms.
4. Roll out dough to a quarter-inch thick.
5. Use a two-and-a-half- to three-inch cookie cutter to cut dough into circles. Place about one teaspoon of blueberry pie filling in each circle, pinching to form triangle shaped cookies.
6. Bake for 14–15 minutes.
7. For the glaze: mix together icing sugar and lemon juice. Drizzle on top of cooled hamentaschen if desired. Sprinkle with coconut and/or lemon zest if desired.