In a large mixing bowl or food processor, beat together one stick of cold butter (sliced), ½ cup of sugar, and 1 teaspoon of vanilla extract.
Add one egg. Mix well.
Add 1½ cups of white flour and ½ cup of arrowroot flour. Mix on medium-low (or use your hands) until the dough feels like play clay.
Put a ball of the dough on a work surface covered with non-stick parchment paper. (Wrap unused dough in parchment paper and refrigerate until you need it.)
Cover the dough with parchment paper so the rolling pin won’t stick. Roll out the dough to ¼ inch thick.
Use a big cookie cutter to cut a shape. Move the shape to parchment paper placed on a cookie sheet.
Use a small cookie cutter to cut a small shape from the big one. Remove the small shape.
Continue cutting big shapes, moving them to the paper, then cutting out smaller shapes.
Bake at 375°F for about 7 minutes. Remove from the oven.
Stir 1 teaspoon of powdered gelatin into 2 to 3 tablespoons of all-fruit jam.
Spoon a little of the mixture into the opening in each cookie, just to the edges.
Bake for 4 more minutes. Let cool completely until the jam gels.
Gently peel the cookies from the paper. Serve plain, or decorate with icing.
