1) In a large mixing bowl, combine the water, oats, maple or brown sugar, honey, butter, salt, and cinnamon. Let cool to lukewarm, about 10 to 15 minutes.
2) Add the yeast and flours, stirring to form a rough dough. Knead (about 10 minutes by hand, 5 to 7 minutes by machine) until the dough is smooth and satiny.
3) Transfer the dough to a lightly greased bowl, cover the bowl with lightly greased plastic wrap, and allow the dough to rise for 1 hour. Since the dough is warm to begin with (from the boiling water), it should become quite puffy.
4) Divide the dough in half, and shape each half into a loaf. Place the loaves in two greased 8 1/2" x 4 1/2" bread pans.
5) Cover the pans with lightly greased plastic wrap and allow the loaves to rise until they've crowned about 1" over the rim of the pan, about 60 to 90 minutes.
6) Bake the loaves in a preheated 350°F oven for 35 to 40 minutes, tenting them lightly with aluminum foil after 25 minutes, to prevent over-browning. Remove them from the oven when they're golden brown, and the interior registers 190°F on a digital thermometer.
7) Turn the loaves out onto a rack to cool. Store at room temperature, well-wrapped, for several days; freeze for longer storage.
Yield: 2 sandwich loaves.