I adapted this one from:
1 cup buckwheat flour
1 cup sorghum flour
1/2 cup tapioca starch
1 1/2 teaspoons xanthan gum
1 1/2 teaspoons baking soda
1 teaspoon sea salt
1 cup butter or margarine
1 1/2 cups brown sugar
2 teaspoons vanilla
2 eggs, beaten
jam to fill thumbprints
Whisk dry ingredients together.
Add remaining ingredients except jam and beat until smooth.
Cover and chill the dough for an hour.
Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper.
Roll the chilled dough into 1″ balls and place on the parchment lined baking sheet.
Gently press your thumb into the center of the dough to form an indent.
Fill each thumbprint with jam.
Bake in a preheated oven for about 20 to 23 minutes, until the cookies are golden and firm.