Once your milk is cooled, add it to the bowl of a stand mixer or large mixing bowl, add the 40 g water, 30 g sugar, 100 g active sourdough starter, 375 g all purpose flour, and 7 g salt. Stir with a dough hook attachment about 4 times around the bowl or with a large spoon if you are mixing by hand for 1 to 2 minutes until ingredients are beginning to combine and it looks like a shaggy dough mixture. Add the 4 g vanilla and 1 egg. Continue mixing the dough until it becomes completely combined and soft.