Is this made with peppermint or spearmint?
Peppermint. The Peppermint Coffee Syrup is our holiday syrup with the higher-menthol, candy-cane profile, very different from our spearmint Mint Coffee Syrup. The sharper cool is what makes this read as bark instead of cookie. If you want a softer, mojito-style cool, that's the Mint Syrup you want, not this one.
How do you make chocolate cold foam at home?
Whisk ½ cup of cold half and half with 1 teaspoon of unsweetened cocoa powder and a small splash of vanilla syrup until it thickens and holds soft peaks. A handheld milk frother is easiest. The cocoa carries the chocolate layer that the bark gets its name from, and the cream keeps the foam stable on top of the cold brew.
Can I make this without the crushed peppermint garnish?
You can, but the candies are what completes the bark reference (texture and visual both). If you're skipping the peppermint candies, consider crushing a chocolate cookie or wafer on top instead so the foam still has something to crunch through.