In the bowl of a stand mixer, combine the warm milk, yeast, and maple syrup. Let sit until the yeast is foamy, about 5-10 minutes. If you yeast doesn't froth, it be dead. Womp womp. Go buy a fresh packet.
Whisk in the butter and egg until incorporated. With the dough hook attachment, knead in 3 1/2 cups of the flour. Add flour 1 tablespoon at a time until a tacky, soft, but cohesive dough forms. I needed about 4 1/4 cups to accomplish this. Alternatively, you can turn the dough onto a floured countertop and knead by hand, adding flour as needed, for 10-15 minutes until you achieve the needed texture.
Spray the bowl lightly with oil and turn the dough over so both sides are coated. Cover with plastic wrap or a tea towel and let rise in a warm, draft-free place until doubled, about 60-90 minutes.
When the dough is ready, punch it down, flour a clean flat work surface, and roll into a 12 x 16 inch rectangle. Spread with the softened butter from edge to edge. Stir together the brown sugar, cocoa powder, cinnamon, and instant espresso (if using). Sprinkle over the buttered dough, then dust with the chopped chocolate.
Lightly grease a 9 x 13 inch baking dish. Slice the dough into 12 strips. Roll each strip until a, well, roll. Place into the baking dish. Cover and let rise an additional 30 minutes, or up to 24 hours in the fridge.
Meanwhile, preheat the oven to 375 degrees. Uncover the rolls and bake for 18-20 minutes until lightly golden on top. Let cool for at least 10 minutes before frosting.
For the frosting, beat together the cream cheese, butter, powdered sugar, bourbon, and vanilla until fluffy. Ice each cinnamon roll generously. Serve warm with hot coffee!