Mix the warm water and milk. Dissolve the yeast in this mixture.
Equip the mixer with the baking hook. In its bowl, mix the flour, the sugar and the salt. (if you don't a mixer, you can do it by hand)
Add the water/milk/yeast mixture and the melted butter.
Knead at slow speed until you get a homogeneous and elastic dough (about 10 min).
Cover it with a clean cloth and keep it aside in a warm place for 1 to 1h30, or until it has doubled in volume.
Cover a baking sheet with parchment paper, sprinkled with polenta (optional).
Deaerate the dough, then cut it into 12 pieces of equal weight (approximately).
Shape them into balls. Place them into the sheet, and cover both sides with polenta. Slightly flatten them out with your hand.
Keep them aside again for 30-45 min (at this point I cover the baking sheet with food film and place it in the refrigerator overnight, this allows me to bake the muffins the same morning and have them fresh for the breakfast).
Preheat the oven to 180°C (350°F).
In a frying pan, melt down a knob of butter with a drizzle of oil. Place 2 to 3 balls of the dough (depending on the size of your frying pan) and cook them for about 5 minutes. Gently turn over the muffins and cook on the other side for another 5 minutes. Place the muffins in the oven for 10 minutes. Repeat this step with the remaining dough pieces.