Pour the white chocolate chips in a microwave-safe bowl. Melt chocolate in the microwave, checking/stirring every 30 seconds or so, until chips are completely smooth. Add the Peppermint Extract and food coloring (if desired).
Spread the melted white (or green) mint chocolate onto a parchment-covered baking sheet. Refrigerate chocolate slab for at least 15 minutes while you make the other layer.
Add the semi-sweet chocolate chips to a microwave safe bowl. Microwave as you did with the white chocolate until chips are melted and completely smooth, stirring every 30 seconds.
Once the white (or green) chocolate layer has “set,” take baking sheet out of refrigerator and spread the melted semi-sweet chocolate layer over the top.
Return baking sheet to the fridge or freezer and allow to cool until bark has become completely hard.
Break bark into fairly uniform bite size pieces, and store in a resealable container in the refrigerator for up to 2 weeks.
Using a double boiler, or a heatproof bowl in the microwave, melt the white chocolate chips, stirring until melted and smooth.
Pour half of the melted white chocolate and 1 tsp of Apple Pie Spice Blend onto the cereal squares. Toss to coat, then pour over the remaining melted white chocolate and the other teaspoon of Apple Pie Spice.
Gently continue stirring until cereal squares are evenly coated with chocolate and spices.
Using a sifter (or a spoon and a steady hand), dust snack mix with powdered sugar. Use one cup of powdered sugar to begin, adding up to another 1/2 Cup if desired.
Spread snack mix onto a wax or parchment paper-lined baking sheet, and allow cereal to cool thoroughly before serving.
Store any leftover snack mix in a sealed container for up to one week.
Adapted from A Pumpkin And A Princess.