Add both candy melts and peanut butter to the top of a double boiler (or to a heatproof glass bowl resting in a saucepan with a couple inches of water in it).
Heat the mixture until melted and smooth.
Pour the fudge into an 8x8-inch baking pan lined with a sheet of parchment paper. Allow the fudge to set. Do not refrigerate.
Once completely set, cut the fudge into squares, and if desired, top with decorative sugar cake decorations. Store in an air-tight container at room temperature.
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Notes
*I assume that when this recipe was developed, these three items came in 14-ounce packages. However, product sizes have changed over the years. Ultimately, you will need equal amounts of each ingredient. Adjust your pan size accordingly.