Line a cookie sheet with parchment paper. Set aside.
In double broiler (or a large glass bowl over a shallow pot of boiling water), melt the chocolate over medium-high heat, stirring until completely melted.
Once the chocolate is melted, stir in 1/2 cup of chopped peppermint candies and extract (if desired). Remove from the heat.
Pour the chocolate over the parchment paper and spread the chocolate over a thin layer. Sprinkle the remaining chopped peppermint candies and almond slivers over the top of the chocolate.
Refrigerate the cookie sheet (and freshly poured chocolate) for at least 30 minutes, until the chocolate is hard.
Remove the chocolate from the fridge and break apart with your hands. The bark can be stored in an air-tight container on the counter (no need for refrigeration).