Place flour in the mixer bowl. Add sugar on one side, salt on the other, yeast in a well in the middle. Mix briefly with dough hook.
Add warm milk, eggs, and vanilla. Mix until a firm ball forms.
Add the butter a bit at a time until all added.
Knead until it comes away from the sides easily, ~10 minutes.
Cover with a towel and let sit in a warm place for an hour. Dough should be about doubled.
Knock down and turn out onto a lightly floured surface or a silicone mat.
Knead a bit by hand and shape into a long tube.
Divide into 10 or 12 equal portions (Should be ~83-100-grams each.)
Shape the dough into a roll ~4-5" long and place apart on parchment lined baking sheets, 5-6 per sheet. Give them some room. You might be able to get all 10 on one sheet. (If adding chocolate, form dough flat, sprinkle ~2-3 teaspoons of the miniature chocolate chips, and roll around them.)
Make 3-5 incisions on the top with scissors.
Cover and leave in a warm place for 30-45 minutes. Toward the end of this proving time set oven to 350°F Convection (175°C with fan) with rack in middle.
If desired, brush the top with the egg/water and (optional) sprinkle with chocolate chips or pearl sugar.
Put into the oven and reduce oven temperature to 340°F Convection (170°C with fan). Bake for for 15 minutes, turning or switching racks if desired.
Check for doneness -- thermometer should read 190°F (88°C). Bake another 5 minutes if needed.