In the bowl of a stand mixer, combine all pre-fermented dough ingredients. Place in a warm place for 1 hour (I use the oven with the lights turned on).

When it has doubled in volume, is bubbly, and has an acidic smell, add the bread flour, milk, salt, sugar, and egg. Place it in a stand mixer fitted with a hook attachment. Knead on medium for 5 minutes or until the dough looks more homogenous and pulls easily from the sides of the bowl but still sticks to your hands.

Add the butter in 4 parts and knead each part until it’s completely incorporated (the dough can look like it’s disintegrating but will come back together eventually). When done, knead the dough for 7-10 minutes on medium until it pulls away from the sides of the bowl and you can stretch a small piece of it into a square, creating a film thin enough for light to pass through (windowpane test). The dough should be very soft, smooth, and just a little bit sticky.

Cover the bowl with plastic wrap and leave it at room temperature to proof for 1 to 2 hours, depending on how warm it is in your kitchen, until it doubles in volume.

Punch the dough down and remove it onto a lightly floured working surface. Divide into 15 even pieces (53g each or eyeball it). Shape each piece into a tight ball and place it in the prepared baking pan. If the dough sticks too much, you can grease your hands with a little bit of olive oil.

Cover the pan filled with rolls with plastic wrap and leave at room temperature to proof for 1 hour or until doubled in volume and jiggly.

Meanwhile, preheat the oven to 375F (190C).

Bake on the middle rack for 13-15 minutes or until the internal temperature is 190F (88C). The top should be a deep brown color and the bread should sound like it’s hollow inside when you tap on it.

Remove from the oven, brush with some melted butter, and enjoy!