Grease the bottom of a 9×13 pan with extra butter. Melt 4 Tbsp butter completely and place in a large microwave safe bowl. Pour marshmallows over the butter and stir around to coat.
Heat marshmallows in the microwave for 30 seconds, stir, microwave for another 30 seconds, and stir again. Add the cereal to the bowl and mix well with marshmallows.
Place the mixture in the greased pan. Get your hand wet and press the mixture evenly in the pan. Add sprinkles and sugar crystals as desired. Cover and place in the fridge to cool for one hour.
Cut into 20-24 squares and place bottom side up on wax paper. Melt white chocolate chips in a microwave safe bowl and heat at 30-second intervals, stirring after every 30 seconds, until chocolate is smooth.
Dip the bottom quarter to third of each treat in the chocolate. Place upside down on wax paper to cool.