Preheat oven to 250 degrees Fahrenheit. Line a baking sheet with Gefen Parchment Paper. Set aside.

In the bowl of a electric mixer fitted with the whisk attachment, combine egg whites and vinegar. Beat at high speed until foamy. With machine running, add sugar a quarter cup at a time. Keep beating on high speed until stiff peaks form, two to four minutes. Beat in the salt and coffee.

Using a large spoon, scoop fluffy mounds, about three inches in diameter, onto prepared baking sheet. Alternatively, you can pipe rosettes with a Wilton’s 1M piping tip. The presentation is not important, as you will ultimately crush the meringue anyhow.

Bake for 45 minutes, then turn oven off and open the door just a crack. Let meringues cool in oven for another hour or so. Freeze until ready to use.

Melt chocolate and butter in microwave. Stir well until smooth. Stir in Cocoa Puffs.

Carefully place into a 9×13-inch pan or a Norpro Mini Cheesecake Pan. Press down crunch to form one uniform layer. If using the Norpro, make sure the sides are even.

Refrigerate until set, about 10 minutes.

Combine cocoa and hot water in a cup, and set aside.

Melt chocolate in microwave. Set aside to cool.

In the bowl of electric mixer fitted with the whisk attachment, whip heavy cream, sugar, and salt on medium speed until mixture begins to thicken, about 30 seconds. Increase speed to high and whip until soft peaks form, 30-60 seconds.

Whisk egg yolks into the cooled melted chocolate. Whisk until smooth and yolks are no longer visible. Add cocoa mixture and whisk some more.

Combine whipped cream with chocolate mixture by hand with the help of a spatula. Mix until streaks are no longer visible and color is uniform.

Pour into the 9-x13-inch pan or transfer to a piping bag (or a resealable plastic bag with a corner snipped off) to pipe into the Norpro. Smooth tops with the help of an offset spatula. (If using the Norpro, make sure sides are clean so next layer is neat. Use a damp paper towel if necessary).

Crush four to five meringues into a bowl. Liberally sprinkle over chocolate mousse layer, pressing down gently. Freeze.

Using a box grater, shave chocolate into a large bowl.

In a saucepan, bring one cup heavy cream to a slight simmer over medium heat. Do not boil.

Pour over chocolate and whisk together until all chocolate is dissolved and no lumps are visible. Cover and refrigerate for two to four hours.

In the bowl of an electric mixer fitted with the whisk attachment, whisk chilled mixture and remaining quarter cup of heavy cream until creamy and slightly thickened.

Cut marshmallows in half and place on a plate. Microwave until they start puffing up (10 seconds). Working quickly, add marshmallows to mixing bowl. Continue whisking at high speed but be very careful and watch closely – the mixture could turn into “butter” very quickly due to the chocolate. As soon as you see the whisk lines become more pronounced, stop. Mousse should be creamy and thick but still a little bit runny.

Gently spread or pipe white chocolate mousse over the chocolate layer. Return to freezer.

To remove mousse from removable bottom pan, run a towel under hot water, squeeze water out, then hold over the bottom of each mousse for a few seconds. Mousse will release easily. I recommend doing this before Yom Tov and returning to freezer until ready to plate.

Plate mousses while still frozen, whether you are using the Norpro or the Cuisipro Scoop and Stack. Make sure to plate about 20 minutes before serving; you want the layers to be creamy and fork-tender.

Crush remaining meringues and sprinkle over mousses just before serving.

Sit back, relax, and rake in the compliments.