How to Make It
In a small saucepan, heat 1/2 cup of the milk to 110°. In a bowl, mix the yeast with the warm milk; let stand for 5 minutes.
In the bowl of a standing electric mixer fitted with a dough hook, combine the 3 cups flour with the sugar, orange zest and salt. On low speed, mix in the yeast mixture, egg yolk, butter and vanilla. Add the remaining 1/2 cup of milk. Knead the dough at medium speed until it is smooth and silky, about 5 minutes. Cover and refrigerate for 1 hour.
Lightly grease a 9-by-13-inch baking dish and line the bottom with parchment or wax paper. In a medium saucepan, combine the butter with the light brown sugar, maple syrup and 1/2 tablespoon of the cinnamon. Bring to a boil, stirring, until the butter is melted and the sugar is dissolved. Pour the syrup into the baking pan.
On a lightly floured surface, roll out the dough to a 12-by-16-inch rectangle, with a long edge facing you. Lightly brush the egg wash over the dough. Combine the granulated sugar with the remaining 1 tablespoon cinnamon and sprinkle it heavily all over the dough, leaving a 1-inch border at the bottom. Starting at the top edge, roll up the dough jelly-roll style, and pinch the bottom edge to seal.
Cut the roll into 10 even slices and arrange the slices, cut side down, in the syrup. Cover the pan with plastic wrap and let rise in a warm, draft-free place until the dough has doubled in bulk and is soft to the touch, 1 to 2 hours.
Preheat the oven to 350°. Put the almonds on a baking sheet and roast until fragrant and golden, 8 to 9 minutes. Let cool, then coarsely chop the nuts.
Bake the sticky buns for 40 minutes, or until the dough is a deep golden brown and the syrup is bubbling. Let cool slightly, then use tongs to transfer the sticky buns, 1 at a time, to a serving dish. Spoon any remaining syrup over the buns and sprinkle with the almonds. Serve warm.