Dissolve the fresh yeast in a little lukewarm water.
Place yeast, flour, brown sugar, milk, water, egg and salt in a food mixer with the dough hook installed. Knead for 10 minutes.
Next, add the softened butter and knead again for 10 minutes. Form a ball and let the dough rise for at least 2 hours in a warm place. (I usually do this step the night before: I cover the bowl with lightly oiled cling film and place it in the fridge overnight.)
Once the dough has risen, divide it into 8 equal portions and let sit for 5 minutes under a tea towel. Form the dough into balls and press down lightly to flatten them. Let the baps stand for about 1 hour on an oiled baking tray.
Preheat the oven at 200 degrees C / Gas 6. Use a pastry brush to coat the baps with milk and sprinkle sesame or poppy seeds on top. Bake for about 20 minutes, or until the buns are golden brown on top. Cool on a wire rack.