Add Jell-O to a bowl and whisk in boiling water until gelatin mix is dissolved. Whisk in orange preserves until dissolved. Stir in cold water. Pour mixture into a shallow 9x13 dish and chill in the fridge until set, at least 2 hours, best overnight.
Preheat the oven to 350 degrees F (180 degrees C). Grease a 12-cup muffin tin.
Whisk egg and sugar together in a bowl until pale and fluffy using an electric mixer. Gently fold in flour until combined.
Fill each muffin hole with 1 heaping teaspoon of batter and spread batter to make sure it covers the entire bottom. Once all 12 holes are filled distribute remaining batter evenly among the 12 holes.
Bake in the preheated oven until the cakes should spring back when lightly pressed, 8 to 9 minutes. Remove muffin tin from the oven and allow to cool in the tin,5 to 10 minutes. Transfer to a wire rack to finish cooling.
Meanwhile, melt chocolate in a microwave-safe glass or ceramic bowl in 20-second intervals, stirring after each interval until chocolate is completely melted, 1 to 3 minutes. Let chocolate cool to thicken slightly.
Remove cooled and set Jell-O from the refrigerator and cut out 12 circles using a 2-inch round cookie cutter. Place 1 Jell-O round on top of each cooled cake. Remove edges of Jell-O so that the melted chocolate can rest on the cake base. Spoon melted and cooled chocolate over the Jell-O and allow to set completely.
