Substituting white chocolate in Julia Child's mousse I've been making chocolate mousse à la Julia Child since I was 12.  I vaguely recall trying it with butterscotch chips, which didn't work.  Now I have high quality white chocolate I'd like to try in lieu of semisweet, but what to substitute for the two liquids, espresso and liqueur/orange juice?

I want this mousse to taste like white chocolate, so orange juice, Cointreau, Amaretto, and coconut milk are out if a quarter cup would compete flavorwise.  Rum may be a safe choice, but I only have Captain Morgan's on hand.  I won't up the liqueur to a half cup.

I appreciate the mocha flavor of the original, and wonder if using espresso would overpower the white chocolate, or if orange juice would any more than rum.  I have a couple more days to figure out what to do.  Suggestions?
Guittard replied to my query after the fact, so I learned firsthand that one should use less liquid because cocoa solids in dark chocolate are absent from white chocolate.  I substituted 1/4 cup milk for the same amount of strong coffee in the original recipe, and the Baker's Premium White Chocolate liquefied.  Melted semisweet doesn't pour like it did, and I was paranoid my mousse wouldn't set.

I studied my liqueur options at the store.  A 750mL bottle of crème de cacao tempted me with thoughts of frozen cocktails, all requiring additional 750mL bottles of other liqueurs, and I didn't want to go there.  The selection of 50mL bottles was limited, but I settled on E&amp;J Vanilla brandy.

When I opened it, there was no essence of vanilla; I smelled only brandy.  The 1/4 teaspoon of vanilla extract I added to the milk was imperceptible, as well.  My attempt at white chocolate mousse was more like a brandy Alexander custard.  My official taster said he wouldn't have known I used either white chocolate or vanilla if I hadn't told him all about it.

His initial "Wow!" and the way he savored it conveyed his appreciation nonetheless.  Brandy made for a good flavoring.  If I found Baker's 4-ounce bars on sale again, I'd forgo using liquid in the melting step, and hope for a less custardy consistency.  I even reduced the butter by 2 tablespoons, and beat the living daylights out of it before folding in the egg whites.  It set, but a spoon won't stand up in it like the original.

Thank you for your advice:)