Melt the dark chocolate and coconut oil together. If you are worried about the chocolate seizing, then use a bain-marie. If it does separate a little, then adding a little oil usually fixes this.
Use a teaspoon to spoon out circles on to a lined baking tray and then use the back of the spoon to spread the mixture out to make it even.
Before the mixture sets, add the sprinkles on top.
Put them in the fridge until set.
Notes
As the toppings are added to the buttons randomly, the nutritional information will not be accurate.