Dissolve yeast in 1/4 cup warm water. Add a pinch of sugar and stir to combine. Let sit for 5-10 minutes until mixture is cloudy, foamy, and has increased in volume.
In the bowl of a stand mixer fitted with a hook attachment, mix together all-purpose flour, bread flour, sugar, and salt. Add yeast mixture, warm milk, and egg. Knead to combine.
Slowly add softened butter, one tablespoon at a time. Mix until incorporated. Continue to knead in machine or transfer to clean working surface and knead by hand until dough is smooth, soft and elastic.
Roll dough into a ball and place in a large bowl. Cover with plastic wrap and let dough proof for 45-60 minutes until dough has doubled in volume.
Preheat oven to 400 degrees F.
Remove dough from bowl and deflate using the heel of your hand. Transfer to a cleaning working surface. Divide dough into 8 equal portions, roughly 2 oz each. Or divide dough into your desired size.
Roll dough into a tight balls and place on a parchment lined baking sheet. Cover with plastic wrap and let rest for 30 minutes until dough has puffed up.
Score tops of dough using a sharp pairing knife. Lightly brush dough with melted butter and sprinkle with pearl sugar. Bake for 12-15 minutes until dough is golden in color.