On the stovetop in a medium saucepan, combine the orange juice and the sugar on a medium-low heat, and simmer until the sugar dissolves. Add the extract and stir well to disperse. Take the saucepan off the heat and evenly sprinkle the packet of gelatine over the surface of the liquid. Stir until there are no lumps and the gelatine is completely dissolved.

Pour about a tablespoon of the orange jelly mixture into each cup of a 12-hole muffin pan. If your pan is nonstick, there's no need to prepare it; if your pan isn't nonstick, you may need to line the cups with parchment paper. Leave in the fridge to set for about 2 hours. When they are chilled, remove the discs from the pan so you can use the muffin pan for the cakes.

Preheat the oven to 350°F. Prepare the muffin pan by spraying each cup with nonstick cooking spray, then set aside.

Place enough water in a pot that is wide enough to fit a mixing bowl without having the bowl touch the surface of the water. Simmer the water to create an indirect heat source on the bottom of the bowl. Whisk together the eggs and sugar on the medium setting of a hand mixer until pale and frothy, about 5 minutes. You want to create lots of air bubbles in the batter, since these cakes contain no leavening agent.

When the mixture is frothy, remove the bowl from the heat and stir in the vanilla extract. Lightly fold in the flour, being careful not to knock too much air out of the mixture. Make sure there are no dry pockets of flour!

Pour one tablespoon of batter in each cup of the muffin pan. Bake in the preheated oven for about 8 or 9 minutes. The cakes should be light in color, so don't think they are underdone if they are a little light. Let cool for a few minutes, then use a knife to gently remove the cakes from the pan and let cool completely on a wire rack.

When the cakes are cool, trim a little off of the edge of each jelly disc (you want the jelly to be a little smaller than the cake). Place a jelly disc on each cake. Melt your chocolate in a heat-proof bowl in the microwave, doing so in small spurts of time to prevent burning. When your chocolate is silky smooth and flows easily, pour it over each cake. Use a spoon to gently coax the chocolate to the edges of the cake, completely encasing the jelly. Before the chocolate dries, press a fork gently into the chocolate and lift to create a pattern that's traditionally found on packaged Jaffa cakes. Let the chocolate dry, then enjoy with a mug of tea!