Preheat the oven to 325°F.

Grease and lightly flour a 9 x 5 loaf pan.

Sift together all-purpose flour, whole-wheat flour, baking soda, and cinnamon in a medium mixing bowl and set aside.

In a large mixing bowl, combine hot water, brown sugar, canola oil, malt syrup (or dark corn syrup), and salt.

Mix the wet ingredients well by hand, but don't overbeat.

Using a spatula, gradually add the flour mixture to the water-sugar mixture until fully incorporated and the batter becomes smooth.

Carefully beat in the eggs with a spatula until incorporated. (The batter should be very thin at this point.)

Pour the batter into the prepared loaf pan.

Bake for 1 hour and 15 minutes. Test for readiness by inserting a skewer.

When the skewer comes out clean, remove the loaf from the oven and let it cool on a rack until it reaches room temperature.

Once cooled, wrap the loaf with plastic wrap and place it in the freezer for 30 minutes to an hour, or until it is firm.

Grate the chocolate bars and set aside.

Take the partially frozen loaf and slice it at 1/4- to 1/2-inch thickness.

Lightly toast the graham tartine slices.

Sprinkle grated chocolate over the top of the toasted slices.

Top with six marshmallows per slice.

Set under a broiler until the marshmallows are golden brown.

Slice each toast into three bite-size servings and enjoy.