In the bowl of a stand mixer, whisk together the flour, sugar, salt and yeast. Add the milk and butter. Mix with beater blade on medium high for 5 minutes.
Remove the beater blade. Cover and let rise at room temperature for 2 hours. Transfer to the fridge and chill for 4 hours.
Heat oven to 450F, with a clean Dutch oven inside to heat up as well.
Liberally flour a piece of parchment paper (slightly larger than a standard sheet of paper).
Scrape the dough out of the bowl onto the parchment. With flour hands, and floured dough, gently coax the dough into a torpedo shape. Cover with plastic wrap and let rest for 30 minutes. It won't get much bigger, just slightly puffed.
Remove the Dutch oven from the oven. Gently lift the loaf, parchment paper and all, into the Dutch oven, and replace the lid.
Put the Dutch oven back into the oven and bake for 30-35 minutes. The top will be golden brown, and puffed up. Allow to cool on a wire rack completely before storing. Store in a sealed bag in the fridge for up to two weeks, or in the freezer for up to two months.