Take a 13×9 baking sheet and line it with wax paper, then spritz it with spray oil to keep treats from sticking.
Melt the butter in a large pot over low heat. When the butter is fully melted, dump in your bag of mini marshmallows and allow them to melt, stirring constantly. When fully melted, remove the pan from heat.
Pour in the cereal and toss until coated with the marshmallow mixture, but try not to over mix it. That will result in a dryer rice krispie treat.
Spread into your prepared baking sheet with a greased piece of wax paper (the paper off your stick of butter works great for this). Allow for the mixture to cool completely before moving on.
Use your shell-shaped cookie cutter to cut out the treats. If the treats seem loose, you can press additional rice krispie mixture into the cookie cutter before releasing the shape onto wax paper.
Reshape the scraps of the krispie treat mixture into the cookie cutter as well, using all of it you can that’s left in your baking pan.
Place your white candy melts into a microwave-safe bowl and microwave on high heat, stirring the mixture every 30 seconds until it’s completely melted. Be careful not to overhead them. If the candy seems too thick, it can be thinned a bit using vegetable shortening or coconut oil. Do not add water to the mixture.
Take your shell krispie treats and dip one side of them into the candy melts. Allow the extra to run back into your bowl.
Place your shell on wax paper and put the extra sugar and pearl on immediately.
Allow them to cool completely before serving or storing.