Pour the graham cracker crumbs into the bottoms of each mason jar. Add a layer of mini marshmallows on top of the graham cracker crumbs (optional).

Place chocolate and butter in a medium-sized bowl.

In a small saucepan, combine the cream, sugar, and salt. Heat over medium and stir constantly until the sugar is completely dissolved and the liquid gently simmers, about 4 minutes.

Pour the cream mixture over the chocolate and butter. Let it sit for a minute to melt the chocolate. Then gently stir for about 3 minutes or until well-combined and smooth.

Using a spouted measuring cup or a spoon, pour the ganache into the mini mason jars. It's okay if it gets a bit messy, you can clean up the tops with a damp paper towel when you're finished distributing the ganache. Fill until about ? of the jars are full. Clean the tops if necessary and place them in the fridge to set the ganache.

Beat the egg whites, vanilla and salt at high speed until foamy. Gradually add the sugar and beat until stiff peaks form, about 4-5 minutes.

Beat in a bit of the marshmallow creme at a time, until it has all been added and the meringue is fluffy and well combined. Fold in the mini marshmallows.

Using a spoon, dollop the meringue into the mason jars. Make sure to push the first few spoonfuls down so that they sit atop the ganache. Make peaks on top of the ganache by pulling the spoon up quickly or twirling the spoon.

Brown the marshmallow meringue with a kitchen torch. If you don't own a kitchen torch, feel free to put them in the oven on "broil" to brown them, but keep a close eye on them because it only takes a few seconds for them to go from toasty brown to burnt!

Refrigerate until ready to serve.