In a double boiler (or, a glass bowl set on top of a sauce pan with 2-inches of water, making sure that the water isn't touching the bottom of the bowl), combine the milk chocolate, tahini, and coconut oil for the magic shell. Cook over medium heat, until the chocolate is fully melted, whisking to combine the ingredients every so often to prevent any scorching. The final mixture should be smooth and homogenous. Transfer to a tall glass and cool slightly.