Preheat oven to 400 degrees.
Mix flour and salt in a large bowl. Cut in shortening using a pastry cutter. Cut in butter.
Add oil and milk and stir until a soft dough forms.
Prepare desired filling mixture recipe.
Roll dough, using a rolling pin, on a lightly floured work surface 1/4" thin.
Use a pizza cutter to cut 3" x 8" rectangles out of the dough. A paper template works great for this. I simply cut a piece of copy paper to size and lay it on the dough then cut around it.
Collect scraps of dough, form into a ball then roll out again to cut more rectangles. You should be able to get 6 rectangles of dough from each recipe.
Poke rectangles with a fork.
Brush egg wash around the edges of each rectangle of pastry dough.
Mix filling ingredients together in a small bowl. Spoon 1-2 Tbsp. of filling on one side of pastry rectangles. Fold the dough over, covering the filling.
Press edges all the way around with a fork (this will seal/glue the edges during baking). Use the fork to pierce a few more holes on the top of the pop tart for venting.
Place pop tarts on a baking pan lined with parchment paper. Brush with egg wash.
Bake at 400 degrees for 25 minutes.
Allow pop tarts to cool. Whisk desired icing ingredients together then spoon icing over each pop tart. Add sprinkles, if desired.