Can I make the components ahead?
Yes. The coffee anglaise and mascarpone whip can be made up to 1 day ahead and refrigerated. Assemble and cook the French toast just before serving for best texture.
What type of brioche works best?
Use day-old, thick-cut brioche (about 1-inch slices) so it absorbs the custard without falling apart. Fresh brioche will become too soggy.
How do I know the custard is fully cooked?
The egg yolks should reach 160°F when measured with a thermometer, or coat the back of a spoon without running off when stirred.
Can I skip the white chocolate?
You can omit it, but it adds sweetness and richness that balances the bitter espresso. Mascarpone alone will be tangier.
Is instant espresso powder necessary?
Yes—it's the signature flavor. Brewed coffee won't provide the same depth. Use quality instant espresso powder for best results.