Whisk all of your dry ingredients for the dough together in a large bowl.
Take out a small bowl and mix your wet ingredients together. Pour the wet ingredients into the bowl with the dry ingredients and fold everything together with a spatula just until a shaggy dough forms. If the dough is too dry to come together, add cold water 1 teaspoon at a time.
Chill the dough in the fridge for 30 to 45 minutes.
Take out two sheets of parchment paper and roll the dough between them to about 1/8-inch thick.
Cut the dough into equal rectangles using a rectangular mold, pizza cutter, or knife.
Place a heaping tablespoon of sugar-free jam onto half of the rectangles, leaving a 1/4-inch border around the edges.
Dot water around the borders of the filled rectangles, top each with a second rectangle, and press the edges together. Crimp the edges firmly with a fork to seal.
Air fry for 8 minutes. You'll know they're done when the edges are lightly browned. Alternatively, you can bake them in the oven on 350°F for 15 to 20 minutes.
Let them cool completely on a wire rack for 30 minutes before frosting.
Take out a bowl to prepare your frosting. Add the ingredients and mix everything together until smooth.
Once the pastries are fully cooled, spread the frosting over your poptarts and serve.