for the cookies

1. In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar together on high speed until light and fluffy.
2. Add the egg and any flavorings and mix on medium speed to incorporate.
3. Add the flour and mix on low speed until the dough comes together.
4. Bake at 350 degrees F until the edges start to turn golden.

for the filling

1. Use a hand or stand mixer to somewhat blend chopped strawberries together.
2. Put in a small pot over medium heat and add sugar and cornstarch. Let it come to a boil, then remove it from heat and stir vigorously with a whisk for two minutes.
3. Cool the filling in the refrigerator (or freezer) until it thickens. Mix it with a whisk to smooth it out before putting it between the cooled cookies.