Butter a 20x30cm baking pan and set aside. In a small mixing bowl dissolve yeast in warm water. Let stand until creamy, about 10 minutes. Place milk, 1/2 cup sugar, salt and 125g butter in saucepan. Heat until sugar dissolves and butter melts. Cool to lukewarm. Add dissolved yeast and set aside.
In large bowl combine flour, eggs and yeast mixture. Stir until smooth and blended. Pour into pan, spreading dough evenly. Let rise in warm place for 45 minutes. Meanwhile, preheat oven to 190 degrees C.
In a small bowl, combine 125g butter, 1 cup sugar and 1/2 teaspoon cinnamon. Mix together and sprinkle over the dough. Bake in preheated oven for 30 minutes, or until the top is golden and syrupy.