Mix the flour, baking powder, sugar, margarine and salt with the food processor and stir in the milk. If the dough is too sticky, add a little flour.
Roll out the dough as thinly as possible on flour and cut into approx. 10 cm long, 7 wide rectangles. Two rectangles are needed for a pop tart
Filling:
Mix the cinnamon, sugar and cornstarch.
Brush a rectangle of pastry with the egg-milk mix and spread the filling generously on top. Cover with a second rectangle of dough, press the edges together well and brush the top again with milk egg. For a nicer look, carefully press the dough along the edge with the knife. Bake at 175 degrees for 10-15 minutes.
Topping:
Mix powdered sugar with a little milk and spread on the cooled poptarts. Decorate with colorful sprinkles if necessary.
Tip:
If you want to do without the topping, you can simply sprinkle some sugar on the Pop Tarts while baking, this will then caramelize very nicely.