Several readers have reported this issue and I have reduced the butter used for filling from 40 grams to 20 grams. Please melt and cool the butter, brush it on the dough and then sprinkle it with the cinnamon brown sugar mixture. Use your hands and press the brown sugar mixture into the dough. Also, make sure the rolls are not being baked in a way too big of a pan. If they have too much room to spread, the filling will leak out.