Heat pineapple juice and milk in a small bowl to about 110 degrees. It should be warm to the touch NOT hot. Add yeast to the liquids and let sit for about 10 minutes to let yeast activate.
Pour mixture into the bowl of a stand mixer with the dough hook attached. Place mixer on low speed and add egg, brown sugar, vanilla and salt.
Turn mixer up to medium speed and begin to add the flour, 1 cup at a time, until fully incorporated. Dough should form a ball around dough hook. If dough is too sticky, add flour, tablespoons at a time. If too dry, add warm water, tablespoons at a time.
Place dough in a lightly greased bowl, cover, and let rise for 1.5 hours or until the dough doubles in size.
Transfer dough to a lightly floured surface and separate into 20 equal sized balls. Transfer those to a lightly greased 13"x9" baking dish. Cover and let rise for another 30 minutes.
Preheat oven to 375 degrees.
Combine 2 tbsp butter and 1 tsp pineapple juice in a small bowl. Brush the tops of the rolls with this mixture.
Bake the rolls for about 18-20 minutes until lightly golden on top.
Remove from oven, let cool, Enjoy!