In a large bowl, mix water, yeast, and 2 teaspoons honey. Let sit for a few minutes while you do the next step.
Melt butter in a large saucepan over medium heat. Add ½ cup honey, salt, and milk. Heat to 120ºF.
Pour the milk mixture into the yeast mixture and stir. Stir in both types of flour, 2 cups at a time. Turn the dough out onto a floured counter and knead for 5-10 minutes, adding more flour as needed to prevent it from sticking to the counter and your hands. Place the dough in an oiled bowl and cover with a lightly oiled sheet of plastic wrap. Let rise for 1 to 1 ½ hours, until big and puffy.
Make the topping
Generously butter two 9 inch cake pans. Spread brown sugar evenly over the bottom of both pans and sprinkle oats and pecans over both. Set aside.
Assemble the rolls
Punch the dough down and knead out all the bubbles. Divide the dough in half, working with one and leaving the other covered with plastic wrap. On a well floured surface, roll the dough into a large rectangle about ¼ inch thick.
Use a pastry brush to spread half the butter on the rectangle.
In a small bowl combine the brown sugar, cinnamon, oats, and pecans for the filling. Sprinkle half of this mixture onto the buttered dough. Roll the rectangle up horizontally, jellyroll style. Use a sharp serrated knife to cut into slices 1-2 inches thick.
Place the rolls in one of the prepared pans. Repeat with the other half of the dough.
Cover the rolls with a lightly oiled sheet of plastic wrap and refrigerate overnight.
Remove the rolls from the refrigerator at least half an hour before baking. Preheat the oven to 350ºF. Bake the rolls for 30 minutes or until lightly brown and baked through.
After removing from the oven, place a plate over the rolls and flip over to remove the rolls from the pan. If the rolls stick, run a thin knife around the edge of the pan and try again.
Make the icing
Combine all ingredients in a small bowl and whisk until thoroughly combined. Spread evenly over the rolls.