Steps
1. In a blender, puree the ripe banana until smooth. 2. In a saucepan, heat the heavy cream until warm. 3. Melt the dark chocolate and mix it with the warm cream. 4. In a separate saucepan, combine agar agar powder, sugar, and water. Bring to a boil, then simmer for 2 minutes. 5. Slowly pour the agar agar mixture into the chocolate mixture while whisking continuously. 6. Pour the mixture into half-sphere molds and refrigerate for 1 hour. 7. Carefully remove the mousse spheres from the molds. 8. Dust with cocoa powder and top each sphere with a maraschino cherry.