In a large mixing bowl combine the softened butter and granulated sugar.
Add the egg, egg yolk, and lemon extract and combine.
Add the baking powder, baking soda, salt, and flour and combine.
Use 1 heaping tablespoon of cookie dough per cookie and shape it into a round ball. Place each cookie on the cookie sheet, 9-12 per sheet.
Bake at 350°F for 8 minutes. Allow to cool for 1-2 minutes before removing the cookies to a cookie drying rack.
Lemon Cream Cheese Frosting
In a large mixing bowl combine the softened cream cheese, softened butter, powdered sugar, lemon zest, and lemon juice. If you want a stronger lemon taste you can add ½ teaspoon of lemon extract.
Assembling the Cookies
Once the cookies have fully cooled, use a pastry bag fitted with a star pastry tip (you can also use a sturdy Ziploc bag with the tip cut off) and fill it with the lemon cream cheese filling. Pipe the filling onto the bottom of a cookie, then use a second cookie to create a sandwich.Or keep it super simple and use a knife to spread the filling.
Notes
Cookie Size: These cookies are designed to be on the smaller side at just over 1 tablespoon of dough per cookie. This helps them to keep the overall size of the sandwich cookie manageable since each sandwich cookie is two lemon cookies and the filling.
Rolling the dough into a ball gives the cookies a nice round shape when baked.
Troubleshooting: If the cookies look too thin or flat add 1-2 tablespoons of flour to the cookie dough.
Lemon Sugar: If you'd like to add an extra special touch to these cookies you can roll the dough in lemon sugar before baking. To do so add ⅓ a cup of granulated sugar and the zest of 1 lemon to a small bowl. Scrunch the sugar and lemon zest together until the sugar becomes fragrant and the lemon zest is well distributed. Then roll the cookie dough in the sugar and place on a baking sheet to bake.