Preheat your oven to 190°C [375°F] or 170°C fan. Line a 33 x 23 cm Swiss roll cake tin with a sheet of baking parchment/greaseproof paper. Set aside.

In a large mixing bowl, add the eggs and both sugars and whisk on a medium - high speed using a standing mixer with a whisk attachment or electric hand whisk. Do this for around 3 minutes, or until the mixture has thickened and is pale in colour. The mixture should leave a ribbon trail when you lift the whisk (it continuously falls from the whisk for a few seconds).

Sift in the flour, cocoa powder, and salt. Fold everything together using a metal spoon. Do this carefully so as not to knock any air out. The mixture will be ready when there are no flour or cocoa powder streaks left. Be sure to scrape any build up off the spoon and gently work it back into the mixture!

Pour the mixture onto the lined tray. Using an offset palette knife or ordinary cutlery knife, gently spread the mixture out into an even layer. Get into the corners if you can.

Bake on the middle shelf of your oven for 10 - 12 minutes. Your sponge will be ready when it is well risen, the sides are shrinking away from the edges, and the surface is firm to touch.

Once baked, leave your sponge cake to cool for around 10 minutes on the tray before transferring upside down onto a wire rack and carefully peeling the paper off.

While your sponge cake is cooling, whip your cream.

Add the cream and icing sugar to a large mixing bowl.

Using an electric hand whisk or standing mixer with the whisk attachment on, whip the cream and sugar together on a high speed until the cream can hold its shape (i.e. when a quiff of whipped cream remains on the whisk when you lift it out).

Melt your chocolate now. Do this in the microwave with the chocolate in a heatproof bowl, melting in bursts of 20 seconds and stirring in between bursts until completely melted.

Using a cookie cutter of the same size or slightly smaller than your jar circumference, cut out 12 circles of cake from your sponge.

Pipe or spoon a layer of whipped cream into the base of each jar. Top with a circular piece of cake, then a spoon of melted chocolate. If you want to hide some candy/chocolate toppings in each layer, sprinkle a few in now. Pipe or spoon another layer of whipped cream and repeat this step until your jar is full, with the toppings as the last layer. Each jar should fit 2 - 3 rounds of chocolate cake in.

Repeat step 3 for every jar, or until your ingredients are all used up.

Rip up the leftover cake sponge and fill up more jars/ramekins with it, along with any spare whipped cream and sweet toppings.

Cover the jars with their lids. Alternatively, cover the open ends of the jars with aluminium foil/beeswax paper/cling film and secure with a rubber or elastic band.

Refrigerate until ready to serve.