Mix the chocolate dough ingredients in a food processor. Once a dough forms, remove then refrigerate for at least 2 hours.
CHOCOLATE DOUGH
Melt milk, chocolate chips, salt, and brown sugar. Remove the bowl from the heat, and whisk in the butter. Refrigerate then transfer the fudge filling to a piping bag.
MAKE THE FUDGE FILLING
Roll the chilled dough into a 10 x 13 inch rectangle. Using a pastry wheel or a knife, cut out 3 x 4-inch rectangles. Add rectangles to a parchment lined baking tray & brush with egg wash.
PREPARE THE POP TARTS
Pipe fudge filling onto the middle of each rectangle. Place the remaining pastry rectangles on top and seal the edges. Chill for 30 minutes or freeze for 15.
FILL & SEAL
Bake the pop tarts on the lower rack for 20 minutes at 375 degrees. Once cool, add chocolate glaze and sprinkles if desired.