Preheat the oven to 350°F (175°C) and line a large baking sheet with parchment paper.

In a food processor, combine almond flour, coconut flour, granulated erythritol, xanthan gum, and salt. Pulse to combine.

Add the cold cubed butter to the processor. Pulse until the mixture resembles coarse sand.

Add the egg and vanilla extract. Pulse until the dough begins to clump together into a ball. Do not over-process.

Wrap the dough in plastic wrap and chill in the refrigerator for 20 minutes to improve handling.

Place the chilled dough between two large sheets of parchment paper. Roll out to a 1/4-inch thickness in a rectangular shape.

Using a pizza cutter, cut the dough into 16 equal rectangles (approximately 3x4 inches).

Place 8 rectangles onto the prepared baking sheet. Spoon 1 tablespoon of sugar-free jam into the center of each, leaving a 1/2-inch border.

Place the remaining 8 rectangles on top of the jam-filled bases. Use a fork to crimp the edges firmly to seal.

Prick the top of each tart 2-3 times with a fork to allow steam to escape during baking.

Bake for 15-18 minutes, or until the edges are golden brown. Remove from the oven and allow to cool completely on the pan.

Prepare the glaze by whisking together the confectioners sweetener, heavy cream, and extra vanilla until smooth.

Spread the glaze over the cooled pop tarts and top with sugar-free sprinkles before the icing sets.