Combine 1 tbsp of coconut oil and the sugar-free white chocolate in a microwave-safe bowl, heating in 30-second bursts and stirring well between each one. Stop when the mixture is smooth and glossy, with no stubborn chip-shaped lumps.

Place the sugar-free chocolate chips and the remaining coconut oil in a separate microwave-safe bowl, then melt them in the same 30-second intervals with stirring. The dark chocolate should flow easily from a spoon without looking oily or scorched.

Stir 26 drops of peppermint candy extract into the melted white chocolate until evenly blended. The mint aroma should be noticeable but the chocolate should remain smooth and fluid.

Pour the dark chocolate onto an aluminum-foil-lined baking sheet and spread it into a 1/4 inch thick layer, then place it in the freezer for 10 minutes. The surface should lose its wet shine and feel firm when lightly touched.

Cover the set dark layer with the peppermint white chocolate, then sprinkle on the crushed peppermints if using and return the pan to the freezer until firm. Pour gently so the white layer stays bright and distinct rather than disturbing the dark chocolate underneath.

Break the chilled bark into serving pieces. A crisp, sharp snap signals that the layers are set and ready to serve.