Chocolate Covered Espresso Pretzels

1. Preheat the oven to 325 degrees F. Line 2 baking sheets with parchment paper.
2. In a bowl, toss the pretzels, with melted butter and vanilla. In another bowl, mix the brown sugar, espresso powder, and cinnamon (if using). Toss the pretzels with half the sugar, then arrange on the prepared baking sheet. Sprinkle each pretzel with any remaining sugar.
3. Bake for 8-10 minutes, until the pretzels are lightly caramelized. Watch close as the sugar can burn. Remove from the oven, let cool. 
4. Melt the chocolate. Dip each pretzel in melted chocolate and place on a parchment-lined baking sheet. Repeat with the remaining pretzels. Freeze for 10 minutes, until set. Store in an air-tight container in the fridge.