In a mixing bowl, combine warm water, brown sugar, and yeast. Mix together so that the yeast is dissolved into your mixture. Allow for it to sit for 5 minutes.
Add in butter, sea salt, bread flour, wheat flour, oats, and sunflower seeds. Mix together until well combined. Mold the dough into a ball and remove it from the mixing bowl.
Coat your mixing bowl in olive oil place your dough ball back into your bowl and then turn so that your entire dough ball is covered in oil. Cover your bowl with a damp towel and place it in a warm, dry location to rise. Allow the dough to rise until it is double in size. This should take about 1 hour to 1 1/2 hours.
Once double in size, uncover the dough, and punch down. Turn the dough out onto a lightly floured surface and kneed. Then mold into two loaf shapes. Place loafs into greased bread pans. Cover and allow to rise until double in size once more. This should take about 45 minutes to 1 hour.
Preheat your oven to 375F. Bake for 20-30 minutes, or until a toothpick inserted in the center comes out clean.
Prepare egg wash. Combine two eggs with water and whisk together. Brush on top of your loaves of bread. Sprinkle oats and nuts. Bake again for 5 minutes, or until the eggs have been fully cooked.
Remove from oven, turn the bread out and allow for it to cool. Serve warm or after the bread has cooled. Enjoy!