Begin by putting the crumbs, butter, sugar, and salt into a bowl and mixing them together until the

mixture has the texture of damp sand. Press this mixture firmly into a 9 by 13 inch baking dish—even

though it might be tempting just to pour it in and move on with the recipe, you have to press it down

since otherwise it will fall apart when you try to cut it. After that, put it in the refrigerator for thirty

minutes while you get on with preparing the other ingredients.

Start by melting the chocolate by putting it over a pot of water which is just beginning to simmer until

the chocolate has become smooth, after which allow it to cool a bit. In a separate bowl, beat one cup

of cream until soft peaks appear. In another bowl, mix the egg whites with a small amount of salt until

a foamy texture is obtained, then gradually add the six tablespoons of sugar while still beating the egg

whites. Continue beating until stiff, shiny peaks are achieved. Mix the melted chocolate into the

whipped cream and then gently fold in the egg whites—do not rush this step since you would then

lose the light and fluffy texture. Lastly, add the vanilla.

Cover the crust with half of the mousse. If you want to add some peanut butter or Nutella, put a small

amount on top and gently swirl it in, making sure that the little pockets of flavour are still

visible—those are wonderful. Then spread the rest of the mousse over the top and smooth it down.

In order to prepare the ganache, put the chopped chocolate into a bowl. Heat the cream and butter in

a saucepan until they just start to simmer, and then pour them over the chocolate. Leave it for two

minutes and stir from the centre outwards until it has become smooth and shiny. Let it cool for about

ten minutes so that it thickens a little but remains pourable. Pour the ganache on top and allow it to

flow naturally down the sides.

Cover it with plastic wrap and chill it for a minimum of four hours, ideally overnight; the longer it

remains in this state, the better the flavours will taste together.

If you would like to eat it, take it out and leave it there for about fifteen minutes. For each cut, place

your knife into some hot water in order to get clean slices. Then add some whipped cream, chocolate

shavings, berries, or caramel on top.

Buy good chocolate because it is the primary ingredient and if you use the cheap chocolate chips the

flavour will be affected; for that reason it's worth spending a little more and purchasing a good bar to

notice the difference.

Don't rush the chilling process. Even if you think, "It's already been two hours and it appears to have

set, so I'll proceed," don't do it. Rather, let it chill for at least four hours altogether. It is only after it has

been left overnight that the true effect takes place.

When you are using egg whites—since it is they that give the mousse its lightness—you should make

sure that both your bowl and your beaters are completely clean and free from any grease, as even a

small amount of fat will stop them whipping properly and will result in something that looks like sad

foam rather than the nice stiff peaks. It is worth washing the bowl and drying it thoroughly before you

start.

You must remember to press down on the crust since that actually does make a difference when

you're cutting clean slices.

The recipe is both tolerant and easy to modify. For instance, if a person is unable to eat gluten, all you

need to do is substitute gluten-free cookie crumbs and you'll be fine. If you want to make it vegan, use

coconut cream and dairy-free chocolate together with aquafaba (that is, the liquid remaining from

canned chickpeas) in place of the egg whites. The final product turns out surprisingly like the original.

You can also add two tablespoons of instant espresso to the melted chocolate since it has no coffee

flavour but rather makes the chocolate taste more intense and richer. Although this may seem odd it

actually does work.

So long as it is tightly covered with plastic wrap, the dish will stay fresh in the refrigerator for up to five

days; since the dessert is already served cold there is no requirement to reheat it, all you need to do

is take it out about fifteen minutes before eating so that it has time to soften.

I have now made it so many times that I almost don't need the recipe any more, and that is precisely

what a good recipe ought to do: it should be simple enough to remember and good enough to prepare

repeatedly. It is able to serve a large number of people without causing you the slightest stress and at

the same time manage to impress people without in the least being complicated. Even though

chocolate lasagna looks as if it has taken a long time to prepare, I can assure you it hasn't.

Should you try it once, you will probably end up back in the kitchen once more, posing to yourself the

very question that I always ask, namely "What if I add something else next time?" And to be honest,

that is in fact the real problem with this recipe — and in reality that isn't a problem at all