Measure the flour, sugar, salt and yeast into the bowl of an electric stand mixer.
Lightly mix the ingredients together using the dough hook.
Slowly pour in the warm milk, and continue mixing until everything comes together into a rough dough.
Add the butter, one tablespoon at a time. Once the butter has been fully incorporated into the dough, add the next tablespoon of butter.
Once all of the butter has been added, continue kneading the dough on medium speed for about 15 to 20 minutes.
The dough is ready when it is soft and smooth, and also slightly elastic in texture when you try to stretch it. If you poke the dough softly, it should bounce back right away.
Lightly oil a large mixing bowl.
Place the dough inside the bowl.
Cover the dough with a clean tea towel.
Leave the dough somewhere warm for 1 to 1.5 hours, or until the dough has doubled in size (see Kitchen Notes below).
Once the dough has doubled in size, punch back the dough to release all of the air.
Gently knead the dough a few times, and then knead in all of the raisins.