Once grain mixture has cooled, add honey, butter, and yeast and mix on low speed until combined. Add flour mixture, 1/2 cup at a time, and knead until cohesive mass starts to form, 1 1/2-2 minutes; cover bowl tightly with plastic wrap and let dough rest for 20 minutes. Add salt and knead on medium-low speed until dough clears sides of bowl, 3-4 minutes if it does not clear sides, add 2-3 Tbsp additional flour and knead until it does.

Continue to knead dough for 5 more minutes. Add seeds if using and knead another 15 seconds. Transfer dough to lightly floured counter and knead by hand until seeds are dispersed evenly and dough forms smooth, round ball. Place dough in large, lightly greased bowl; cover tightly with plastic and let rise at room temperature until nearly doubled in size, 45-60 minutes.

Grease two 9×5 inch loaf pans. Transfer dough to lightly floured counter and divide in half. Press 1 piece of dough into 9×6 inch rectangle, with short side facing you. Roll dough toward you into firm cylinder, keeping roll taut by tucking it under itself as you go. Turn loaf seam side up and pinch it closed. Repeat with second piece of dough. Spray loaves lightly with water or vegetable il spray. Roll each loaf in oats to coat evenly and place seam side down in prepared pans, pressing gently into corners. Cover loaves loosely with greased plastic and let rise at room temperature until nearly doubled in size 30-40 minutes. Dough should barely spring back when poked with knuckle.

Thirty minutes before baking, adjust oven rack to middle position and heat oven to 375F. Bake until loaves register 200F, 35-40 minutes. Transfer pans to wire rack and let cool for 5 minutes. Remove loaves from pans, return to rack, and let cool to room temperature, about 2 hours, before slicing and serving.

Storage: bread can be wrapped in double layer of plastic wrap and stored at room temperature for up to 3 days. Wrapped with additional layer of foil, bread can be frozen for up to a month.