2 cups gluten-free flour blend (add xanthan or guar gum, according to package directions if flour does not contain any)
1/2 cup yellow cornmeal
1/2 teaspoon salt
10 tablespoons (1 1/4 sticks) unsalted butter, room temperature
2/3 cups granulated sugar
2 teaspoons lemon zest
3 large egg yolks
1/2 teaspoon vanilla extract
4 tablespoons black currant jam (or other jam of your choice)
Preheat oven 350 degrees. Whisk together flour, cornmeal and salt in large bowl.
With mixer, cream together butter, sugar and lemon zest 2-3 minutes until light and fluffy.
Beat in egg yolks. Add vanilla. Add flour and cornmeal mixture. Mix until no flour pockets remain.
Shape rounded tablespoonfuls of dough into balls.
Place on parchment-lined cookie sheet 1 inch apart.
Bake 5 minutes and remove from oven.
If not too hot, use thumb (or use end of a wooden spoon handle or anything that works)
to make a deep indentation in each cookie.
(Dip thumb or spoon, etc. in ice water before each press.)
Edges will crack when you do this.
Return to oven for another 5 to 8 minutes, until bottoms are golden.
While cookies are still warm, fill centers with jam.
Transfer to rack to finish cooling.