Place 4 cups of flour in a mixing bowl and make a hollow in it with the back of a spoon. Crumble fresh yeast or sprinkle dry yeast in the hollow, fill with the lukewarm milk, add a pinch of sugar and mix a little to incorporate some of the flour. Let the sponge sit in a warm place for 15 minutes.
After the yeast is activated and showing strong growth, add the salt, the egg, 7 tablespoons of softened butter and 3/4 cup of sugar to the milk and mix the dough, incorporating the flour as you go.
You may also use a stand mixer for this step. Continue mixing until the dough is smooth and forms a ball. Add a little more flour if necessary. Form dough into a ball, place in a greased bowl, turning the dough once and cover. Let rise 15 to 30 minutes.
Roll the dough out to 1/2 inch thickness on a lightly floured board and transfer to a jellyroll pan (10 x 15 inches). Let it rest again for 15 minutes while preheating oven to 375°F.
Dimple the top of the dough all over, using your fingers or the back of a wooden spoon. Mix 1/2 cup of sugar and 2 teaspoons of cinnamon together and sprinkle evenly over dough. Cut 9 tablespoons of butter into small flocks and spread it evenly over the dough.
Bake for 25 minutes, or until cake is done and the sugar/cinnamon mixture has melted together and caramelized a little. If you feel the need, turn on the broiler for the last 3 minutes of baking, watching carefully so that the topping does not burn.
Optional: Mix 1/4 cup of sugar with enough water to dissolve the sugar (1/4-1/2 cup) and brush this sugar water on the hot cake right after you take it out of the oven.
This cake freezes well. After defrosting, crisp it up a few minutes in a 350°F oven.
Tip: Make this cake the modern way. Add instant dried yeast and all dough ingredients to a bowl and mix together to form a smooth dough. Allow 30 minutes to rest, then proceed as above.