Combine the 40 grams of whole flax seeds with 60 grams of warm (not boiling!) water. Set aside for at least a 1/2 hour or until you are ready to use. The flax will absorb the water and plump up.
In the bowl of a stand mixer, combine the 1 cup (or 3/4 cup and 2 T. if using honey) warm water and yeast. Add a pinch of sugar. Stir to dissolve yeast, then wait for it to bubble a bit so that you know it’s active.
Add the sugar or honey, 2 cups (280 grams) of the bread flour (reserve 1/2 cup for later), and salt. Stir with a heavy duty scraper until blended, then stir in your extremely soft butter and ground flax. Stir until blended.
Put the mixing bowl on the stand mixer and beat with the dough hook for about 30 seconds or until very well mixed. Remove from the stand and scrape in the soaked flax seeds and about half of the reserved 1/2 cup of flour.
Return to mixer stand and let the hook knead. Dough should still be sticking to the sides of the bowl at this point. Add remaining flour gradually until most of the dough clings to the hook. Some dough will still stick to the sides. Stop and scrape the sides and continue to knead on low, stopping again to scrape bowl, for about 5 minutes.
Grease a large bowl with oil or spray with cooking spray. Scrape the dough into the bowl and turn so that it is slick (or give it a spritz of cooking spray). Cover the bowl with greased plastic wrap and allow it to double in size (about 1 to 1 1/2 hours).
Punch down the dough. I like to plop it out on a pastry mat, press it into a rectangle and turn it a few times. It should be easy to handle and not at all sticky at this point. Press into a big rectangle, then roll into a tight cylinder, pressing air out as you go, and shape into a loaf.
Press into a greased 8 1/2 x 4 1/2 inch loaf pan. Cover with greased plastic wrap and let rise again. This should take about 45 minutes to an hour Dough should rise up over an inch in the middle.
Bake at 375 degrees F for the first 20 minutes, then reduce heat to 350 and bake for another 20 minutes until browned and appears done.
Let cool for a good 2 hours before you slice it. This is a soft bread, but if you refrigerate it for a bit it will be firmer and easier to slice.