Ingredients :

• Mascarpone — This is what provides the hold and the melting quality. Use full-fat, never light — the reduced-fat version makes the cream runny and hard to work with. Any supermarket brand will do, even the cheapest one.
• White chocolate — Here, quality truly changes everything. Industrial white chocolate is often too sweet, with artificial vanilla aromas that overpower everything else. Opt for Lindt white dessert or Valrhona Ivoire if you can — the difference in the final mousse is clearly noticeable: rounder and less chemical.
• Heavy liquid cream — Full fat with at least 30% fat content, and cold — really cold. If your kitchen is hot, put the bowl and whisk in the freezer for 15 minutes beforehand. Cream barely out of the fridge in hot weather won’t whip, or will whip and immediately collapse.
• Ladyfingers (Biscuits à la cuillère) — They absorb milk in seconds. Too little time in the milk and the center remains dry and hard. Too long and the biscuit disintegrates — the charlotte won’t hold when unmolded. A one-second soak per side, no more. It’s fast, and that’s intentional.