Add the multigrain flour to the bowl of a stand mixer or a large heat-proof mixing bowl. Pour in the boiling water, and carefully stir the flour and water with a rubber spatula until it forms a thick paste. Stir in the butter until well combined. Let the mixture cool for about 20 minutes.
Once the multigrain mixture is warm to the touch and not hot, stir in the honey until thoroughly combined. Stir in the yeast (and vital wheat gluten if using, in that order). It’s important to make sure the mixture truly is lukewarm before adding the yeast. Let stand for 10 minutes to activate the yeast.
Add the all purpose flour, ¼ cup at a time, and knead until the dough ball is smooth. This will take about 10-15 minutes. The dough should be slightly sticky, but should not stick to a rubber spatula. Soft dough makes soft bread, so do not use more flour than necessary!
Use the rubber spatula to clean the sides of the bowl, and form the dough into a smooth ball. Cover the bowl with a plate, and let it rise in a warm place for 45 minutes to 1 hour, or until the dough doubles in size.
Once the first proofing is done, sprinkle 1 teaspoon salt over the dough and knead again for another 5 minutes to make sure the salt is evenly distributed.
Shape the dough into a smooth dough ball, cover with a plate, and let it rise again in a warm place for 45 minutes to 1 hour, or until the dough doubles in size. If you are proofing the dough in the microwave like I do, you’ll need another large mug of boiling water for the second proofing.
While the dough is proofing, grease 2 loaf pans (9” x 5”) with cold butter and set them aside. I use cold butter, as it’s easier to handle and goes on in a thin layer. I simply take a cold stick of butter, peel back the wrapper, and rub it along the inside of the loaf pans to coat.
After the second proofing is done, cut the dough into two equal portions. Knead and roll each piece into a loaf shape with a smooth top. On a clean work surface, spread the rolled oats in a thin layer.
Very lightly brush the top of the loaves with water and gently flip the moistened top onto the thin layer of rolled oats. The oats will cling to the loaf. Then carefully place the loaves, oat-side up into the greased pans. Allow to rise for 1 more hour before baking, repeating the proofing protocol as in the first and second proofings.
When you’re halfway through the last proofing, preheat the oven to 375°F. When the third proofing is complete, bake the loaves in the middle of the oven for 35 minutes, until golden brown. If you tap the bread, and it sounds hollow, it’s done.
Cool for about 5 minutes, and carefully remove the hot bread from the pans. Transfer to a cooling rack to prevent the bread from steaming inside the loaf pan. Slice and serve!