Line two cookie sheets with parchment paper. Set aside.
Roll out both pie rounds with a rolling pin, you can use a tiny bit of flour to keep it from stick. I try to roll and manipulate the dough so it becomes a square. It's easier to cut the rectangle shapes if you can do that. If not, you'll just have some extra dough. You can use that make little pie dippers or shapes if you like.
Use a pastry wheel or knife to cut as many rectangles as you can into the dough. You want them to be small enough to hold in your hand like a pop tart, but big enough to stuff 2 to 4 pieces of Caramilk in them.
Place half the dough rectangles on the cookie sheet, spacing them about an inch or two apart. Place 2 to 4 pieces of Caramilk in the middle of each shape. If you want them to taste more like Samoas you can add a tablespoon of coconut to each one. I did it with half of mine.
In a small bowl whisk the egg and the water (or milk) for the egg wash. Brush a small amount around the top edges of all the bottoms pieces of dough. This will help seal the pop tarts. You just want to brush it on lightly around the edges so when you pinch the dough it seals perfectly. Set the egg wash aside, you'll need it again.
Now place the top pieces of dough over each piece and press down slightly with your hand to even it out a bit. Press the edges down with your fingers, then take a fork dusted with flour and press it down on the edges to seal each piece properly. You can use a pastry wheel to trim any uneven pieces.
Now take a fork and poke a few holes in the tops of each pop tart. Brush the tops with the remaining egg wash, lightly.
Place the cookie sheet in the oven, and bake for about 8 to 12 minutes, you want the top of them to turn a nice light golden brown. Remove from oven and repeat the process with the second cookie sheet.
Allow tarts to cool slightly on the pan for a minute or two, then transfer to a cooling rack and let them cool completely.
While they are cooling, it’s time to make the Nutella ganache.
Scoop the Nutella into a medium size bowl. Set aside.
In a heavy saucepan heat the heavy cream over medium heat until it just starts to bubble up nicely around the edges. Let it come to a boil then quickly pour it over top of the Nutella you placed in the bowl. Whisk until it starts to thicken. You can add more Nutella if you want it thicker, or you can add more heavy cream if you want it thinner. Everyone has different preferences so just roll with yours.
Allow the ganache to cool quite a bit (3 to 5 minutes) then use an offset spatula to smooth the Nutella ganache over each pop tart. Toss some sprinkles over top while the ganache is still wet so they stick properly.
Serve with a big old Nutella loving smile.
You can forgo the Nutella ganache and use powdered sugar over top of these as well. Or do a variety of each. That's what I like to do.