Boil some water and measure out 1 1/4 cups. Add to a large bowl or the bowl of a stand mixer. Add the rolled oats, salt and butter and stir to combine. Let stand 20 minutes, to soak and cool. *Be sure your mixture has cooled enough before you add your yeast to the bowl. If it's too hot, you will kill your yeast. Use a thermometer to test the temperature. It should be around 110F before you add the yeast. If you don't have a thermometer, let cool 5 minutes more and make sure it's just lukewarm.
Add the yeast to the lukewarm water. Stir and let stand 5 minutes.
Once the oat mixture is cooled enough, add the honey, proofed yeast mixture, whole wheat flour and the 1st cup of all purpose flour to the bowl. Mix to combine with the kneading hook. With the mixer running, begin adding the 2nd cup of flour in small increments, letting it mix in before adding more. Continue adding this cup and additional flour, if needed, until you have a quite moist dough, but one that wraps around the hook and cleans the bowl in spots. It may still have a sticky bit at the bottom of the bowl. That is ok. Remove the dough to a floured surface and knead a few minutes, adding a bit of flour as needed, to prevent it from sticking to your hands or the work surface. Form into a ball. Place into a greased bowl. Cover with plastic wrap and let rise until doubled, about 1 hour.
Grease an 8x4-inch loaf pan and set aside.
Remove dough to a lightly floured surface and gently deflate it by pressing down on it with your palms. Form the dough into a rough oval, about as long as your loaf pan (set your loaf pan next to your work area to judge the length). Flip the dough over and pinch in from the sides to the centre of the dough, pinching a seam down the middle. Pinch in the ends, as well. Flip it back over, right side up. Scatter some rolled oats on your work surface. Lightly brush your dough with water (not too much - just a light coating), then roll it over the oats, rolling to cover top, sides and bottom. Place dough into your prepared loaf pan. Spray a piece of plastic wrap with cooking spray and cover the top of the pan tightly. Allow to rise until doubled again, about 45-60 minutes.
Preheat oven to 350F.
When dough is ready, remove plastic wrap and bake in preheated oven for about 45 minutes, or until the loaf tests at least 200F with an instant read thermometer. If you don't have a thermometer, insert a tester in the side and into the centre. It should come out clean and dry. If in doubt, leave it in the oven a few extra minutes, as you probably won't hurt it. *It is unlikely that your loaf will over-brown, but check it after about 35 minutes and if it looks like it may over-brown, lay a sheet of aluminum foil loosely over-top for the last part of baking.
Remove loaf from oven and immediately remove from pan to a cooling rack to cool completely before slicing.
This bread keeps well for several days stored at room temperature, well wrapped. You can also freeze this bread up to 3 months, though it will best if used within the first month.Be sure to read the Tips section above the recipe card for more tips for making this bread.