Start by making the sponge!

Heat up the milk until it reaches 38ºC or 110ºF (I put mine for 30 seconds in the microwave) and sprinkle the active dry yeast right on top. Wait about 10 minutes for the magic to happen!

Next, in a bowl of your electric mixer combine half the flour, the and the milk/yeast mixture. With a rubber spatula, mix the ingredients together until combined. Now cover the top of the mixture with the remaining flour and let rest uncovered for about 40 minutes.

To prepare the dough, add sugar, salt, 1 cup flour, and beaten eggs to the sponge in the bowl of your mixer. Using the hook attachment, mix for a minute on low. Now add the remaining 1/2 cup of flour and keep mixing. When incorporated, increase speed and beat for about 15 minutes. During mixing, the dough should wrap around the hook and slap the sides of the bowl. If this does not happen after 10 minutes, add up to 3 tablespoons additional flour. Continue to beat a full 15 minutes.

Meanwhile, grab the room temperature butter and with the mixer on low, add the butter a couple of tablespoons at a time, scraping the bowl with a spatula from time to time. Once you have added all the butter, keep mixing the dough on medium speed for about 10 minutes. If the dough is not coming together after 3 minutes, add in 1 tablespoon of additional flour (I did that).

At this point the dough should feel somewhat smooth, soft, and sticky. Transfer it to a well-oiled bowl, cover with plastic wrap and a towel and let it rise in a warm place until it doubles in size (I left mine resting for 2 hours). Deflate dough by lifting a section, and letting it fall back into the bowl. Cover tightly with plastic wrap and chill 4 to 6 hours in the fridge.

After this time, the dough is ready to be used in any brioche recipes! Look how much it rised in the fridge. I just roll it out on a floured surface then roll it back in, and place it in a heavily buttered loaf pan. Now cover with plastic wrap and let rest for about 1 hour.

At this point, you’re ready for baking!

Beat up the egg with the milk and brush the loaf across all its surface. Put the bread in the oven for about 45–55 minutes at 180ºC or 355ºF. Take it out of the oven and let it cool down on a wire rack.