Line an 8x8-inch square baking pan with parchment paper and lightly grease the sides of the paper so the marshmallow doesn't stick as much.

Lay graham cracker squares in an even layer in the base of the lined baking pan.

Place marshmallows in a large heat safe bowl. Melt the butter in the microwave or in a saucepan over low heat and then drizzle it over the marshmallows. Place the bowl in the microwave and heat for 2-3 minutes at 30 second intervals on medium power stirring between each interval until the mixture is smooth and it looks like marshmallow fluff or shaving cream.

Scrape the marshmallow cream into the pan over the graham crackers and spread it out evenly using an oiled knife. Use a torch to toast the surface lightly if desired (this is optional).

Combine chocolate and coconut oil in a medium heat safe bowl and place in the microwave. Heat on medium power for 30 second intervals stirring between each interval until the chocolate is completely melted and smooth. Pour the chocolate over the marshmallow layer and spread it out evenly. Sprinkle crushed graham crackers, mini marshmallows and flaky salt on top while the chocolate is still fluid.

Place the pan in the fridge until the chocolate is set and then slice with a hot, dry, lightly oiled knife. Enjoy!