Heat the butter in a saucepan over medium heat. Let cook until it gets really roasted and brown (but not black). Place aside to let the little brown crumbs set on the bottom of the pan. Carefully pour the liquid butter in another container (you can use it for the madeleine recipe which is also in the magazine) until just about one tablespoon with all the solid crumbs is left.
Mix the starch with 3 tablespoons of milk. In a big saucepan, heat the rest of the milk, sugar, glucose and brown butter crumbs and let it cook, then pour in the starch and whisk until it thickens.
Fill in an airtight plastic bag and let it cool very quickly (I use to put very cold water in the sink and then let the bag cool down in it). Pour the mixture in your icecream machine and let it run until it gets thick and creamy. The icecream can be stored in an airtight container in your freezer until you serve it.
Spread a thin layer of butter on the brioche slices and bake them in the oven at 180 °C until golden brown. Let cool and crumble over the scoops of brown butter icecream.