Combine heavy cream, milk and cocoa powder in a medium saucepan over medium heat. Whisk constantly until cocoa is dissolved and mixture comes to a simmer.
Remove from heat and pour over the chocolate. Let stand for 2 to 3 minutes and then whisk gently until all chocolate is melted. Mix in vanilla and cinnamon. Add the cayenne and chili powder to taste.
Fill popsicle molds (recipe makes 3-1/2 cups) and freeze about 4 hours, until set. If the frozen fudgesicle is too spicy, coat one side in sugar after removing from mold. To do, sprinkle sugar on wax paper or a plate. Place 1 side of fudgesicle on sugar.