Mix yeast and 15 g sugar. Melt 40 g fat in a pot, remove from heat and add cold milk. Put the flour in a bowl. Add 25 g sugar, salt, egg, lukewarm fat milk mixture and yeast.
Knead with the dough hooks of the hand mixer to a smooth yeast dough. Cover and leave to rise in a warm place for 30-45 minutes.
Melt 25 g fat in a pot. Mix 75 g sugar and cinnamon. Briefly knead the yeast dough with your hands and roll out into a rectangular plate (approx. 38 x 40 cm) on a floured work surface.
Brush the plate with the liquid butter, leaving an approx. 2 cm wide edge on one long side. Sprinkle the dough evenly with the sugar-cinnamon mixture. Roll up the dough sheet to the uncoated long side and press the seam edge down well.
Cut the roll into 18 approx. 2 cm thick slices and put a lollipop stick in each slice. Press the slices flat with your hands.
Preheat a waffle iron for Belgian waffles (2 square waffles of 10 x 10 cm each) and spread with oil. Place 2 cinnamon buns on each stem in the waffle iron and bake at medium heat until golden brown.
Bake all the cinnamon buns one after the other, cleaning the waffle iron in between (cinnamon-sugar caramelised in the waffle iron).