Dissolve the yeast and sugar in 120 ml (4 fl oz) water between 38 - 46°C (100° - 115°F). While the yeast is fermenting, mix sweet potato, 1 cup (8 fl oz) 250 ml milk, salt, melted butter, and the nutmeg if desired, in a large mixing bowl. When the yeast has developed a foamy head, add it to the sweet potatoes and mix well. Stir in the flour, 100 g (4 oz) at a time. When the dough is stiff, place it on a floured board and knead at least 5 minutes, continuing to add flour until the dough is very elastic and not sticky. and cover.

Place in a warm, draught-free spot until dough has doubled in bulk, about 1 hour. Knock back the dough. Divide the dough between two buttered 23 x 12.5 cm (9 x 5 inch) loaf tins. Or cut off golf-ball-sized pieces of dough, pat them into balls and put them into buttered muffin tins. Put the dough in a warm place, cover and let it rise until it has once again doubled in bulk.

Bake in a preheated oven at 200°C (400°F) gas mark 6, about 20 minutes for the rolls and about 35 - 40 minutes for loaves.

Make a glaze for the bread by beating together one egg and the remaining 30 ml (2 tbsp) milk. Brush the glaze over the top of the loaves or rolls during the last 10 minutes of cooking.