Add 1 tbsp of sugar and yeast into the warm milk. Mix well then let stand until frothy (about 5 minutes).
Add the flour, the remaining sugar, powdered milk, eggs and yeast mixture into a heavy duty mixer bowl with dough hook. Knead until everything is well blended. Add salt. Knead until the dough comes together. Add butter. Knead until smooth and elastic (if the dough is being stretched it will not get torn and look transparant).
Put the dough in a greased big bowl. Cover with plastic wrap and allow it to rise in a warm place until doubled.
While waiting for the dough to proof, make the topping
Put the sugar, butter and vanilla extract into a mixer bowl. Beat until light and fluffy. Stir in flour and mix until a thick dough forms. Divide dough into as many flavor as you want. Add flavor or food colors. Knead until well mixed. Cover pieces with plastic wrap and put in the fridge until ready for use.
When the dough is ready, turn it out onto a lightly floured surface. At this point, take the topping out of the fridge. Divide the dough into 24 even pieces. Fill each dough with one cube salted butter and shape each piece into a ball (make sure to pinch the dough really well so the filling will not leak). Place the dough buns on a parchment-lined baking sheet. Flatten each of them a little bit.
Devide the topping into 24 pieces. Sprinkle flour onto work surface lightly. Roll out each pieces into a round shape as same as the diameter of the bun surface.
Transfer the topping rounds to the buns using an offset spatula. If the paste doesnt want to stick naturally, use a pastry brush to apply dots of water on the underside before applying to the buns. Score lines into the topping to resemble the ridges on a seashell by using a small knife with a pointing tip. Allow the buns to rise on the baking sheet until doubled in size.
Preheat oven to 350F. Bake the buns for 10 minutes or until lightly brown
Store the leftovers in an airtight container.
