Butter the tin well. You can use a bread tin, a special brioche tin, or a lasagna pan. Take the dough out of the bowl onto a lightly floured surface. If you are using a brioche tin, divide the dough into a big blob and a small blob, about 80% and 20% of the big ball. Form a big tight ball and a tiny little tight ball. Place the big ball in the mould and then stick the little ball to the top, using some milk or melted butter as glue.
If you want to use a regular bread tin, go for it. Grease the tin with butter and gently roll the dough into a little sausage and place it in the tin, or make a longer sausage and place it into the tin in a fancy S shape, or mould 6-8 individual balls and tuck them side-by-side into the tin...whatever you want. Just remember: the dough should only come 1/3 of the way up the sides of the tin. Brioche dough expands to over twice its original volume.
Cover the dough and let it rest for one hour or so. If you have chilled the dough, it will take 2-3 hours to rise.
Preheat the oven to 180 C/350 F.
Beat together the ingredients for the glaze and brush it on the top of the dough.
Pop it in the oven and bake the brioche for 30 minutes. Remove from the oven and gently take it out of the tin and transfer it to a wire rack. Let it cool completely before you cut or tear into it.