1. Melt the yeast in the milk.
2. Blend yeast, milk, flour, sugar, and eggs in a mixer with a kneading hook until obtaining a smooth mixture.
3. Gradually add the butter in the mixer.
4. Put the dough to a bowl, cover it and let it rise for about 90 minutes until its volume has doubled.
5. Punch the dough with a fork and put it in the fridge for an hour.
6. Roll out the dough until it is about 2.5 cm thick, then place it in a baking pan with baking paper, and freeze for a night.
7. Cut the dough into identical 5×15 cm rectangles, put them on a baking pan with baking paper, and let rise for 30 minutes, until they have doubled in volume.
8. Turn on the oven to 356° C. Bake the brioche rectangles for 20 minutes, until they’re golden brown.
9. For the mascarpone cream, blend all the ingredients in a mixer until obtaining a smooth, stable cream.
10. To assemble the brioches, slice the rectangles horizontally as if you’re preparing a sandwich.
11. Add a little mascarpone cream using a piping bag to one half of the brioche.
12. Generously garnish with the fresh red berries, and cover with the other half.
13. Add the powdered sugar on top.