Line a cookie sheet with wax or parchment paper and set aside.
In a medium microwave-safe bowl, microwave the yellow chocolate melts for 45 seconds. Remove from microwave and stir. Continue to microwave in 10 second increments, sitting in-between, until melted and smooth.
Fill each cookie mold with 2 tablespoons of the melted yellow chocolate. Place an Oreo cookie on top and then spoon additional melted chocolate over the Oreos, up to the top of each mold.
Chill for 30 minutes to allow the chocolate to harden.
Once chilled, gently pop each cookie out of the mold and place on the lined cookie sheet.
With the red decorator icing, pipe 2 hearts for the eyes of each cookie.
With the black decorator icing, pipe a smile on each cookie. (Feel free to experiment with different shaped smiles to get your ideal look.)
Notes
Store in a single layer, in an airtight container for up to 4 days.