Prepare Syrup: In a saucepan, combine water and honey, bring to a boil, then remove from heat.
Mix Chocolate: Add chopped couverture and cocoa to the syrup, wait to soften, then mix until smooth.
Combine with Granola: In a bowl, mix granola (half powdered), cinnamon, cognac, and walnuts with the chocolate mixture.
Form Roll: Spread the mixture on parchment paper, form into a roll, wrap, and freeze.
Coat with Chocolate: Cut the frozen roll into slices, dip each in melted couverture, and let set.
Serve: Once the chocolate has set, the cariocas are ready to be served.