you will need:
one or more silicon ice cube trays - i use the heart shaped ones from ikea. the simpler the shape, the more successful you will be.
dark chocolate or chocolate chips
melt the chocolate in a double boiler, or in a bowl/pot over boiling water, or in the microwave if that's how you roll. if you want a milkier, meltier chocolate, you can add rice or almond or coconut milk at this point. whisk it in and get it nice and creamy.
put a layer of chocolate at the bottom of the ice cube cup. spoon a little bit of nut butter. top it up with more chocolate.
you can now freeze these, or simply let them cool and harden. delicious. once they are hardened, you can pop them out of the silicon tray easily.