Heat the chocolate in a microwave safe bowl uncovered on high for 1 minute. Stir then microwave in 30 second increments until the chocolate is melted and smooth (1-2 minutes longer). The chocolate should not exceed 90? or it will not be shiny.  

Paint 1 tbsp worth of chocolate into the silicone molds using the back of a spoon or a silicone brush.

Let cool in the refrigerator for 5 minutes then add another coat and another, letting them set in the fridge in between. You will want 3 coats in all. Save any remaining chocolate for finishing. 

Let the chocolate cups set/cool in the fridge for another 10 minutes to harden.

Meanwhile in a small bowl mix the hot chocolate mix packets, peanut butter powder, and mini marshmallows. 

Remove the chocolate hemispheres from their molds. Fill half of them with the dry hot chocolate mixture. 

Heat a pan on the stovetop until warm. To seal the chocolate bombs, take each top hemisphere and place it on the warm pan just until it starts to melt (a few seconds). Quickly remove it and set it on the hot chocolate filled hemisphere. Press gently and leave to cool and seal. 

Heat the peanut butter and coconut oil in the microwave, mix well. Add it to a piping bag or ziplock bag with the corner cut to drizzle the chocolate bombs and add the sprinkles (if desired). 

To serve: Heat 8 oz of whole milk per chocolate bomb in a pan or the microwave. Set the chocolate bomb in the bottom of a mug and pour the hot milk over it. Stir and enjoy!