To make Vanilla Maple Butter:
Whip butter and 1/4 cup powdered sugar together until smooth; stir in honey and vanilla. Set aside.
Cut the bread lengthwise into 1/2" slices, without cutting through the bottom crust. Rotate the bread 90 degrees and slice the bread again into 1/2" pieces, without cutting through the bottom crust. Spread more vanilla maple butter in between all cuts. This doesn't need to be perfect - just make sure there is lots of butter in between all the cuts. Combine sugar and cinnamon. Generously sprinkle in between all cuts. (You may have extra butter and cinnamon sugar). It will just depend on how large your bread loaf is. Wrap in foil; place on a baking sheet. Bake at 350 degrees for 20-25 minutes, until bread is warm. Unwrap cinnamon bread and place on serving platter. Combine powdered sugar and milk - adding milk until you get the consistency desired. Drizzle icing over bread and serve immediately.