Prepare the dry ingredients: In a large bowl, whisk together the bread flour, white whole wheat flour, flaxseed meal, salt, and seeds.
In a large microwave-safe bowl, microwave the water and milk until slightly warmed than bath water until it reaches 115 degrees F, about 1 minute. In the bowl of a stand mixer fitted with the paddle attachment, add the warm water and milk mixture, then add in the oats, butter and honey. Mix on medium speed until well combined, about 30 seconds. Sprinkle the yeast over the top and allow the mixture to sit for 5 minutes.
Add the dry ingredients and mix with a wooden spoon until just incorporated, then fit the mixer with the dough hook attachment and knead the dough on medium-low speed for 8 to 10 minutes. The dough will be slightly sticky, but if it is sticking to the sides of the bowl after kneading for a few minutes, add 1 to 2 tablespoons of flour.
Cover the bowl with plastic wrap and a towel and let it stand in a warm place until doubled in size, 1 ½ hours. This may take more or less time depending on the weather or temperature in your home. Tip: If your kitchen is cold, I like to preheat my oven to the lowest temperature possible (100 to 130 degrees F). Once preheated, turn the oven off, place the bowl of dough in the oven, and keep the door slightly ajar – this will help the dough to rise more quickly. The dough is done rising when you press a finger into it and the indentation stays or springs back very slowly.
Grease an 8 ½ x 4 ½ inch loaf pan or an 8x4 inch loaf pan with nonstick cooking spray. (This size of pan is best for this bread, a 9x5 inch tends to be too big.)
Lightly flour a clean surface. Turn the dough out onto the floured surface then use your hands to pat the dough down into an 8x12-inch rectangle. Roll the dough into an 8-inch long log, tucking the ends underneath and sealing the bottom by pinching the ends together. Place in a prepared pan. Cover with a towel and allow the dough to rise again for 45 minutes to 1 hour or until 1-inch above the brim of the pan.
While the dough rises, place a rack in the middle of your oven, then preheat your oven to 350 degrees F.
Once bread is ready and has risen, gently brush the top of the loaf with milk, then sprinkle with oats. Bake for 35 to 40 minutes or until bread is golden brown on top and makes a hollow sound when tapped. A thermometer inserted into the loaf’s center should read 190 degrees F. Remove the bread from the oven, allow it to cool for 5 minutes, then turn bread out onto a wire rack. Allow bread to cool completely before slicing. Store the bread at room temperature well-covered for up to 5 days or freeze for up to 3 months.