Preheat the oven to 180C/350F.
Line a large baking tray with parchment paper and set aside.
In a large mixing bowl, prepare the Greek yogurt dough with sugar and mix well until combined.
Using your hands, shape the dough into a thick, smooth ball.
Flour a kitchen surface and add a tablespoon of flour on top of the ball of dough. Transfer the ball of dough onto the floured surface, and knead several times.
Using a rolling pin, roll out the dough, forming a rectangular shape, about 12 inches by 6 inches.
Using a sharp knife (or pizza cutter), slice once length-ways, and 7 times the other way, to form 16 uniform rectangles.
Place 8 of the rectangles on the lined baking tray, evenly spaced apart.
Place 1 tablespoon of jam onto each rectangle.
Place the other 8 rectangles on top of each one.
Using a fork, press along each side of each pop tart, sealing it up completely.
Using a pastry brush, brush the tops of each pop tart with milk.
Bake the pop tarts for 15-20 minutes, or until golden on top.
Allow pop tarts to cool before glazing.
While the pop tarts are cooling, prepare your glaze by combining the powdered sugar with the vanilla extract and yogurt. Whisk until a thick frosting remains.
Using a spoon, spoon out frosting over the tops of each pop tart, spreading it slightly.
Top with sprinkles, if desired.
