Preheat oven to 350 degrees. Place almonds in a single layer on a rimmed baking sheet and toast until fragrant, about 10 minutes, shaking the pan halfway through. Line three rimmed baking sheets with parchment paper. Top two of the baking sheets with cooling racks; set aside.Advertisement
In a medium saucepan, combine the sugar, water, toasted almonds, and cinnamon. Cook over medium-high heat, stirring constantly, until sugar becomes golden, then starts to crystallize, and almonds are completely coated, about 8 minutes. Pour the almond mixture onto the parchment-lined baking sheet. Transfer to the freezer or refrigerator to chill for 15 minutes.
Place the chocolate in a heatproof bowl and set over a pan of simmering water. Stir until melted. Add the chilled almond mixture, stirring until nuts are thoroughly coated. Divide between the two cooling rack-lined baking sheets. Separate almonds with a fork. Place baking sheets in refrigerator until chocolate is set, 3 to 4 minutes.
Place cocoa powder in a large bowl and add the almond mixture. Toss to coat, shaking off excess cocoa powder. Store in an airtight container for up to 1 month.