Put a piece of chocolate on top of one shortbread and top with marshmallow. Place on baking sheet.
Place baking sheet under broiler for 2-3 minutes, watching carefully until marshmallow is toasted.
Remove from oven and carefully top with shortbread and press down.
Spread strawberry jam or your favorite jam on shortbread before placing on top of marshmallow.
If using hazelnut spread instead of chocolate, spread on shortbread not going in oven. Place marshmallow on 1 shortbread and toast. Spread hazelnut spread on second shortbread and press down on toasted marshmallow.