1) Make the mousseline cream first (so it’s fully cold)

• Take the butter out of the fridge early so it’s soft.
• Split the vanilla pod, scrape the seeds, add seeds + pod to the milk in a saucepan.
• Warm the milk, then remove from heat and infuse for 1 hour.
• In a large bowl, whisk egg yolks with sugar until lighter.
• Add sifted cornstarch and whisk until smooth.
• Remove the pod. Pour the warm vanilla milk in gradually, whisking constantly.
• Return everything to the saucepan and whisk over medium heat until the cream thickens and briefly boils.
• As soon as it thickens, add 50 g butter and mix well.
• Transfer to a clean bowl and cover directly on the surface with cling film.
• Cool completely (not lukewarm), then whisk a few seconds to loosen.
• Add the remaining butter little by little while whisking on medium speed.
• Whisk 8–10 minutes more, until smooth, glossy, and firm enough to hold its shape.

2) Make the brioche base

• In a stand mixer bowl, add flour, sugar, salt, and milk powder.
• Start mixing on medium speed and add instant yeast.
• Lightly beat the egg and add it while mixing.
• Pour in lukewarm milk, then orange blossom water, until the dough comes together.
• Knead until smoother, then add soft butter gradually while kneading.
• Cover and let rise in a draft-free spot for at least 2 hours.
• Deflate the dough and press into a 22 cm pan lined with baking paper.
• Let rise again until doubled or even tripled in volume.

3) Bake, cool, and fill

• Brush with egg yolk + milk.
• Sprinkle generously with sliced almonds.
• Bake at 180°C for about 15 minutes (adjust to your oven).
• Cool completely on a rack.
• Slice the brioche horizontally (gently, with a serrated knife).
• Pipe/spread a generous layer of mousseline cream.
• Chill until serving for cleaner slices.