Line a baking sheet with foil and coat with an even layer of coconut cooking spray. Lay the graham crackers out on the baking sheet in a single layer. Set aside.
Add the chopped semisweet chocolate to a heatsafe mixing bowl set over a pan of simmering water. Add the coconut oil to the bowl with the chocolate and allow it to melt. Heat, stirring, until smooth, 2 to 3 minutes. Leave the mixture in the pan, over the water, until ready to use.
In a separate bowl, add the chopped chocolate candies and candy bars and mix to combine.
Spoon the dulce de leche into a microwave-safe bowl and microwave in 15-second increments, stirring in between to make sure it doesn't burn, until slightly softened and more spreadable. The time needed will vary on your microwave--roughly 30 to 90 seconds.
Scoop the warm dulce de leche onto the graham cracker base and spread it nearly to the edges using an offset spatula.
Give the melted chocolate and coconut oil mixture a quick stir and pour it over the dulce de leche, spreading it evenly with a clean offset spatula. Working quickly, sprinkle the candies over the top of the dulce de leche.
Transfer the baking sheet to the fridge and chill, uncovered, until set, about 2 hours. Once chilled, carefully remove from the baking sheet to a cutting board. Using a long serrated knife, cut the slab into 30 roughly 2-inch squares. Smaller is better as they're rich! Serve cold or at room temperature.