Whisk 250 ml of reserved cherry syrup with 2 tablespoons of cornstarch until smooth.

Bring to a simmer in a small saucepan, stirring until glossy and thick (1–2 minutes).

Fold in drained cherries, 2 tablespoons of Kirsch, and sugar if needed. Cool completely.

In a saucepan, whisk milk, sugar, cocoa, cornstarch, and salt until no lumps remain.

Warm over medium heat, stirring, until steaming.

In a bowl, whisk egg yolks. Slowly stream in a ladle of hot milk, whisking, then pour back into the pan.

Cook, stirring constantly, until thick bubbles plop (2–3 minutes).

Take off heat; whisk in chopped dark chocolate and vanilla until smooth.

Press parchment or plastic wrap onto the surface and cool to room temp, then chill.

Beat cold cream, powdered sugar, and vanilla to medium-soft peaks.

For extra hold, beat in mascarpone or chill 10 minutes and finish to soft-medium peaks.

If using Kirsch, add 1 tablespoon at the end and whisk briefly.

Scatter half the cake cubes into your trifle bowl. Sprinkle with cherry syrup and optional coffee.

Spoon on half the cherry compote.

Spread half the chocolate custard to cover.

Dollop a layer of whipped cream.

Repeat layers with remaining components, ending with a generous cloud of cream.

Finish with chocolate curls and cherries on top.

Chill at least 6 hours (overnight is best) so flavors marry and the cake softens into the custard and cherries.