Coffee Jelly (Japanese Coffee Jelly Dessert)

Steps

1. Soak the gelatin sheets in the cold water, one at a time so they don't stick together. Leave them for 10 minutes, until soft and limp like wet fabric.
2. Brew the coffee and pour it into a saucepan. It should be hot, between 160 and 175°F (70 and 80°C), steaming but not simmering; if it has cooled, rewarm it gently without boiling. Add the sugar and stir until it has completely dissolved.
3. Off the heat, squeeze the gelatin in your hand and drop it into the coffee. Stir for 1 minute, until no translucent strands remain. Skim the foam off the surface with a spoon: it would cloud the top of the jelly.
4. Rinse a square dish about 6 inches (15 cm) across with cold water without drying it, then pour in the coffee: it should be a little over 3/4 inch (2 cm) deep. Let it cool for 30 minutes at room temperature, cover, and refrigerate for at least 4 hours, ideally overnight. It's set when it pulls away from the edge in one clean block when you press it with a finger.
5. Just before serving, pour 150 ml of very cold cream into a chilled bowl with the powdered sugar. Whip for 2 to 3 minutes with a hand mixer to soft peaks: the cream holds the marks of the beaters and droops into a soft curl when you lift them. Keep the rest of the cream in the fridge.
6. Set the bottom of the dish in hot tap water for 10 seconds and run a knife around the edges. Cut the jelly into 3/4 inch (2 cm) cubes with a knife dipped in hot water and wiped between cuts, then lift them out with a thin spatula.
7. Pile the cubes in shallow bowls or on plates. Spoon a generous dollop of whipped cream in the center, drizzle the remaining 50 ml of cream over the cubes, then top the cream with a mint leaf and a coffee bean. Serve well chilled.