For the brioche:
1/3 cup whole milk
2-1/2 tsp yeast
3-1/2 cups flour
1/3 cup sugar
1-1/2 tsp salt
5 large eggs
1/2 lb butter
Heat milk to 100 degrees (no warmer). Sprinkle yeast over milk and wait 10 minutes.
Combine flour, sugar and salt in a mixer bowl with a dough hook. Add the milk/yeast mixture along with the 5 eggs. Mix on low until it comes together as a rough dough. Increase speed to medium and mix 10 minutes.
With mixer on low, add the butter, a couple tbsps at a time – butter MUST be soft but till cool. If it is too warm, it will ruin the recipe.