Dissolve the yeast and 2 tbsp sugar in 120 ml (4 fl oz) warm water (between 38 ¢â‚¬â€� 46°C (100°-115°F). Meanwhile, melt the butter and add it to the milk. When the yeast has developed a foamy head, add it to the milk. Mix in the mashed potatoes, remaining sugar, salt and eggs. Stir in the flour, 100 g (4 oz) at a time, until dough is stiff. Knead it on a floured board 5 minutes or so, until dough is very elastic and has lost its stickiness.

Put the dough in a large oiled bowl. Cover and put in a warm place. Let the dough rise until it has doubled in bulk, 1 - 1 1/2 hours. Knock back the dough. Divide it in half. Put the dough in two 23 X 23-cm (9 x 9 in) square baking tins. Cover the tins and let the dough rise until it has again doubled in bulk.

Make the topping. Combine ingredients in a small saucepan. Heat, stirring often, until butter is melted and sugar dissolved. With your finger, gently make shallow identations all over the tops of the two loaves. Spread the topping across the bread, letting it pool in the indentations. The topping will melt and spread during the baking, so it is not necessary that the bread be completely coated.

Bake the bread in a preheated oven at 190°C (375°F) gas mark 5 for 25-30 minutes. Cut into 9 squares.