How to Make It
In a standing mixer fitted with the dough hook, dissolve the yeast in 1 cup of the warm milk and let stand for 5 minutes. Add the bread flour, salt and 3 tablespoons of the sugar and mix at medium-low speed until a soft dough forms, about 5 minutes. Add the softened butter and mix at medium-low speed until completely incorporated, about 5 minutes longer. Cover the bowl with plastic wrap and let stand at room temperature until the dough has risen slightly, about 1 1/2 hours.
Line two baking sheets with parchment paper. Punch down the dough and divide into 8 pieces. Roll each piece into a narrow 8-inch-long baguette and transfer to the prepared baking sheets. In a small bowl, whisk the egg yolk with 1/2 tablespoon of the sugar and the remaining 2 tablespoons of milk. In another small bowl, combine the cinnamon with the remaining 3 tablespoons of sugar. Brush the tops of the loaves with the egg wash and sprinkle generously with the cinnamon sugar. Let stand at room temperature until slightly puffy, about 30 minutes.
Preheat the oven to 375° and position racks in the lower and middle thirds of the oven. Bake the loaves for about 20 minutes, until golden and risen, shifting the pans from top to bottom and front to back during baking. Transfer the pane al latte to racks to cool slightly, then serve warm.