Stir 1 teaspoon sugar into warm milk and sprinkle with yeast.
Let stand 5 minutes or until the surface is frothy.
Stir gently to moisten any dry particles remaining on top.
Sift flour, 1/4 cup (50 g) sugar and salt into a large bowl.
Melt half the butter; cool slightly.
Refrigerate remaining butter.
Lightly beat melted butter and egg into yeast mixture.
Beat into flour mixture to make a dough.
On a floured surface, knead dough until smooth and elastic.
Cover and let rise in a warm place 1 hour.
Grease two 13x9-inch (33x23-cm) cake pans.
Preheat oven to 425°F (220°C).
Roll out dough to fit greased pans; place in pans.
Make small hollows in the surface of dough.
Cut refrigerated butter into small pieces and place in hollows.
Mix remaining sugar with cinnamon; sprinkle over cakes.
Bake 25 minutes.
Cool in pans then cut into slices.