*Place frozen dough on a greased pizza pan. Cover with sprayed plastic wrap and let thaw at room temperature for 4-5 hours.
Roll out the dough into a circle onto a piece of parchment paper. Use a little flour to keep it from sticking, if needed.
Roughly chop the graham crackers and chocolate bar into desirable chunks. Set aside. Melt chocolate hazelnut spread in a bowl in the microwave for 15-30 seconds, to an easily spreadable consistency. Set aside.
Preheat a gas grill until nice and hot, then turn the heat down as low as it will go.
Brush oil on one side of the dough. Place the oil side down onto a preheated grill. Cook for 2-3 minutes, checking for the dough to look puffed, and golden brown on the bottom. Lightly brush the top side of the dough with oil, and flip it over.
Immediately slather the chocolate hazelnut spread over the cooked side of the dough and top with mini marshmallows, chopped graham crackers, and chocolate pieces. Close the lid and cook 2-3 more minutes until the bottom of the crust is golden and the marshmallows on top puff slightly.
Remove the s’mores pizza from the grill onto a large cutting board. Grease a pizza cutter with cooking spray and cut the pizza while still warm. (The cooking spray keeps the marshmallows from sticking.) Enjoy immediately.
To cook in the oven: Preheat oven to 425 degrees Fahrenheit. Cook crust for 5 minutes. Remove, slather hazelnut spread, and top with marshmallows, graham crackers, and chocolate pieces. Return to oven for another 5-8 minutes until the crust browns and the marshmallows puff up and brown slightly.