Preheat the oven to 180C/350F and grease and line two round 8 inch cake tins.

Place the oil, eggs, vanilla and sugars into a large bowl or the bowl of your stand mixer and beat until smooth and well combined, 1 minute on med-high speed.

Add in the flour, cocoa powder, baking powder, bicarb and salt and mix until just combined.

Add in the melted chocolate and mix on low until well combined.

Add in the sour cream and mix on low-medium for 30 seconds-1 minute until well incorporated and smooth.

Divide the cake batter between the two cake tins and level with a spatula/wooden spoon.

Place in the oven for 30-35 minutes, until risen and an inserted skewer into the centre, comes out clean.*

Leave the cakes to cool in the tins for at least 30 minutes before transferring to a wire rack to cool completely.

Once cool, make the meringue - wipe all bowls, whisks, beaters etc. with a kitchen towel dampened with lemon juice to get rid of any grease. Make sure you use either glass or metal bowls as plastic can affect how big your egg whites get.

Place around 4 cups of water in a large saucepan and place on a medium heat. Bring to a boil and then turn down to simmer.

Place the egg whites, sugar and water into a large heatproof bowl and, using a hand mixer, mix until combined, 10-15 seconds.

Place the heat proof bowl onto the saucepan (make sure the water does not touch the bottom of the bowl) and beat with a hand mixer on med-high speed until the mixture has reached 70C/160F and all the sugar has dissolved, around 10 minutes. The mixture will be past the transparent cloud stage and will be a solid white, but still a little runny.

Once the mix has reached the correct temperature, take off the heat and change to a whisk attachment. Add in a pinch of cream of tartar. Whisk until the bowl is cool to the touch, 15-20 minutes. You want stiff peak - when you remove the whisk the peak will be upright and won't droop over.

To assemble the cake: Level the tops of the cakes with a serrated knife/cake leveler.

Place one cake top side up on a plate/cake board and place just under 1/2 of the meringue onto the cake.

Smooth with an angled spatula, then take the second cake and place it bottom side up.

With the remaining meringue, either spread or pipe it onto the top of the cake. I used a large star nozzle to pipe around the edges and then used a small spatula to spread the meringue in the middle.

Drizzle the cake with the homemade/store bought salted caramel sauce, reserving some for when you serve the cake.

If you have a cook's blow torch, lightly "toast" the meringue on top of the cake, if desired.

Cake will keep covered, in the fridge, for 3 days - take the cake out of the fridge 45 minutes before serving.