In a bowl, combine flour, sugar, salt, and yeast.
Slowly add in milk, condensed milk, and egg, mixing on low speed.
Once dough forms, add softened butter in pieces, mixing until smooth.
Transfer to a floured surface and knead for 8-10 minutes until elastic.
Place dough in a greased bowl, cover, and let rise for 1.5-2 hours.
Once doubled in size, punch down and shape into a rectangle.
Roll the dough into a log and place it in a greased loaf pan.
Cover and let rise for another 1-1.5 hours until nearly doubled.
Preheat oven to 350°F (175°C). Brush dough with egg wash.
Bake for 35-40 minutes until golden brown.
Remove from oven and immediately brush with condensed milk glaze.
Let cool before slicing and serving.