Break the dark and milk chocolates into small, even pieces. Melt them gently in a heatproof bowl set over a saucepan of simmering water, stirring frequently until smooth. Alternatively, melt in a microwave-safe bowl in 30-second intervals, stirring well between each.

Pour the melted chocolate evenly into silicone spoon molds or silicone ice cube trays. If using ice cube trays, insert small wooden sticks or plastic spoons into each mold while the chocolate is still soft.

Freeze for 30 minutes, or until the chocolate is completely set and firm. Carefully remove the chocolate spoons from the molds.

If desired, melt the white chocolate in the same manner and drizzle over the hardened chocolate spoons. Immediately sprinkle with mini chocolate chips, sprinkles, or mini marshmallows to decorate.

To serve, stir one chocolate spoon into 1 cup/240 milliliters of hot milk until fully melted. Store the chocolate spoons in an airtight container in the refrigerator for up to two weeks.