Sift the flour and salt into a bowl and leave in a warm place. Dissolve the yeast and sugar in warm (105 F) milk (M-Waved). Let froth, then mix in the butter. Stir all the liquid into the warm flour and beat well until smooth and elastic.
Cover and proof in a warm place for 50 minutes or until doubled in bulk. Turn onto a well-floured board and knead, working a little more flour if necessary to make the dough easier to shape. Round up the dough, roll into a thick sausage shape and (using the sharpest knife you have) slice into 8 to 10 portions, each about 1 1/2 ~ 1 3/4 inch thick.
Shape each one into a round with straight sides. Put onto a greased baking sheet. Cover (use greased plastic wrap) and put in a warm place to proof for 30-40 minutes or until springy to the touch.
Leave room for expansion and be careful not to over-proof, as the muffins will get flabby and lose their shape. Warm and grease the bakestone lightly. Lift the muffins carefully onto the bakestone and cook over very moderate heat for 8-10 minutes until pale gold underneath.
Turn and cook the other side. Wrap in a cloth and keep warm if cooking in batches. To serve, insert a knife in the side, pull the top and bottom slightly apart, and insert slivers of butter.