Coffee and Milk Mousse

Rehydrate the gelatin in ice water.
Combine the heavy cream for both of the mousses and whip until it forms a thick ribbon when the whisk is lifted.
Make the milk mousse.
Put the milk, sugar and vanilla in a mug, and microwave for about 1 minute until the sugar has dissolved.
While it's still hot, add and dissolve the gelatin and then strain it into a bowl through a tea strainer.
Cool the bowl from Step 3 over ice water.
When it has more or less cooled down, add the whipped cream and mix.
Put the egg white in a separate bowl and whip.
Put the egg white into the mixture from Step 4 in 2 batches and mix quickly with a whisk.
Then mix until fully combined with a rubber spatula.
Pour the mixture into the cups.
You'll add the coffee mousse to the top, so fill the cups to just past the half way mark.
Let them chill and harden in the fridge for 1-2 hours.
Make the coffee mousse.
Put the egg yolk and sugar in a bowl and mix well.
Heat the milk in a saucepan, add the coffee and dissolve it in the milk.
Pour the mixture from Step 9 into the egg mixture from Step 8 little by little, mix, and then return it to the pan.
Heat over a medium to weak flame while mixing.
Remove from heat once the bubbles disappear and it has thickened, and add and dissolve the gelatin.
Strain it into a bowl through a tea strainer.
Place the bowl over ice water until it's chilled.
Then add the heavy cream and mix well.
Check that the milk mousse has hardened, then pour the coffee mousse into the cups and chill in the fridge.
Done!