In a stand mixer, combine 4 cups of all-purpose flour, 1/4 cup of granulated sugar, 2 teaspoons of instant yeast, and 1 teaspoon of salt. Whisk together the dry ingredients until well blended.

Create a well in the center and add 2 large eggs, 1 cup of pineapple juice, 1/2 cup of whole milk, and 1 teaspoon of vanilla extract. Mix on low speed for 5 minutes, then gradually add 1/4 cup of softened unsalted butter while mixing for 2 additional minutes until the dough is a soft, cohesive ball.

Transfer the dough to a greased bowl, cover it with cling wrap, and allow to rise in a warm place for 1.5 to 2 hours until doubled in size.

Punch down the risen dough, transfer to a floured surface, divide into 15 pieces and shape into balls. Arrange in a greased 9x13 baking dish, cover with a cloth, and let rise for another hour.

Preheat oven to 350°F (175°C). Brush the tops with the prepared egg wash and bake for 22-25 minutes until golden brown and hollow-sounding when tapped.

Immediately brush the top with 2 tablespoons of melted butter after baking. Allow to cool for 5-7 minutes before serving.