Amarula chocolate mousse

I rarely bother with desserts, but for Valentine's Day I figured I'd put in the extra effort. Amarula is a South African cream liqueur made from 'the unique fruit of the marula tree'. My girlfriend, being Zimbabwean, has a fondness for this stuff. You can make this mousse with other liqueurs too. Just keep in mind that you may want to reduce the quantities. A single tablespoon of Bailey's, for instance, would most certainly be enough.

170 g good quality dark chocolate, 70% cocoa solids, broken into small pieces
125 mL heavy cream, whipped into soft peaks
4 eggs, separated
60 mL Amarula
50 g butter, cut into chunks
2 tbs white sugar
1/2 tsp cream of tartare
pulp from passion fruit

Heat a little water in a large saucepan until it begins to simmer. Reduce heat. Place a bowl over saucepan and add chocolate. Stir chocolate as it melts to prevent scorching. When melted, add the Amarula and take off heat.. Stir in gently and then add in the butter, chunk by chunk. When fully incorporated, add the egg yolks one at a time.

In another bowl, combine egg whites with cream of tartare. Whisk and whisk and whisk, gradually adding the sugar. When the egg whites hold soft peaks, gently fold egg whites into chocolate mix. Then fold in the whipped cream. Cover and refrigerate for a couple of hours. To serve, spoon carefully into glasses and top with a little passion fruit pulp.