How to Make It
In a small saucepan, melt 1 stick of the butter in 1 cup of the milk over moderate heat. Remove from the heat and add the remaining 1 cup of milk. Pour this mixture into the bowl of a standing electric mixer fitted with a paddle. Add the yeast and beat until dissolved. Add the 6 1/4 cups of flour, 3/4 cup of the sugar and the salt and beat at medium speed until a dough forms.
Transfer the dough to a lightly floured surface and knead until smooth, 1 minute. Lightly oil a large bowl, add the dough and turn to coat. Cover with plastic wrap and let stand in a warm place until the dough has almost doubled in bulk, 40 minutes.
Line the bottoms of two 10-inch round cake pans with parchment paper and lightly butter the paper. Divide the dough into 4 equal pieces. Roll 1 piece into a 12-by-6-inch rectangle about 1/3 inch thick, with a long edge facing you. In a small bowl, combine 1/2 cup of the sugar with the cinnamon. Spread 2 tablespoons of the butter on the dough and sprinkle with 2 tablespoons of the cinnamon sugar, leaving a 1-inch border at one long edge. Roll up the dough jelly roll-style and pinch to seal. Repeat with the remaining dough and cinnamon sugar.
Cut each roll into 8 slices. Arrange the slices in the cake pans, cut side up and about 1/2 inch apart. Cover with a damp towel and let rise in a warm place until the rolls rise slightly, about 30 minutes.
Preheat the oven to 375°. Bake the rolls for 30 minutes, or until golden. Meanwhile, in a small saucepan, combine the remaining 1/2 cup of sugar with the water. Simmer over moderately high heat until the sugar dissolves, 2 minutes. Remove the rolls from the oven and generously brush the tops with the hot sugar syrup. Let cool in the pans for 15 minutes and serve warm.