1 cup butter, softened
1/3 cup sugar
1/3 cup light brown sugar, packed
1 large egg yolk
1 teaspoon strawberry extract
2 1/4 cups all-purpose flour
2 teaspoons cornstarch
1 teaspoon salt
Food coloring, if desired
Cream the butter and sugars together until light and fluffy, about 5 minutes.
Add the yolk and extract, mix until combined.
Add the dry ingredients in batches, mixing until just combined before adding the next batch. Add in food coloring at this stage if you wish to color the dough.
Scoop dough into equal portions and roll between your palms. Place on a cookie sheet and press an indention in the middle with your thumb. Chill the raw cookies for 30 minutes while the oven pre-heats to 375 F.
Pipe the jam into the cookies and bake for 10-13 minutes or until the edges are golden brown.