In a small bowl, combine warm milk with granulated sugar, stir until frothy, and let sit for 5 minutes to activate yeast.

In a large mixing bowl, whisk together all-purpose flour, salt, and the frothy yeast mixture. Add beaten eggs and melted butter, stirring until a smooth dough forms.

Transfer dough to a floured surface and knead for 8–10 minutes until soft and slightly tacky.

Place kneaded dough in a greased bowl, cover tightly and let rise in a warm spot for about 1 hour, or until doubled in size.

Punch down dough gently, divide into 12 pieces, roll into balls, and flatten slightly. Arrange on a parchment-lined baking sheet.

In a separate bowl, cream softened butter and granulated sugar until pale and fluffy. Add all-purpose flour and vanilla extract, mixing until smooth and cohesive.

Chill topping mixture in the refrigerator for 15 minutes to firm it up.

Place discs of the chilled topping onto the buns, cover loosely, and let rise in a warm environment for about 30 minutes.

Preheat oven to 350°F and bake buns for about 18–20 minutes or until golden on top.

Transfer baked Pan Dulce to a wire rack and cool for about 10 minutes before serving.