Place rack in the center of oven and preheat oven to 400 degrees F. With a sharp knife, cut about 1/4 inch off the top of the garlic head, just enough to expose the interior of each clove. Place garlic on a piece of aluminum foil that is large enough to wrap around the head. Drizzle with the olive oil and wrap loosely. Roast directly on the oven rack for 30-40 minutes, until the garlic cloves are soft.
When cool enough to handle, squeeze out the soft garlic from each clove into a small bowl. Mash and stir with a fork until smooth. Stir in the chopped sage and set aside.
In the bowl of a standing mixer fitted with the paddle attachment or a large mixing bowl, stir together the whole wheat flour, all-purpose flour, potato flakes, dry milk, yeast, and salt. Add the butter, honey, and reserved garlic-sage puree. Lightly stir, but don’t worry about combining evenly. Place water and milk in a microwavable measuring cup or small saucepan and heat to the temperature specified by the yeast manufacturer (usually between 110 to 120 degrees F). Pour over the dry ingredients and stir until the ingredients are roughly combined. Switch to the mixer’s dough hook and knead until you have a soft dough, about 5-7 minutes.
Place the dough in a large, lightly oiled bowl, then turn dough to coat. Cover with plastic wrap or a clean kitchen towel and let rise in a warm, draft-free place until it is very puffy, though it may not double in bulk, about 1 to 2 hours. Lightly grease a 9x13-inch pan and set aside.
Gently deflate the dough, then turn it out onto a lightly oiled work surface. Divide dough into 16 pieces. Shape each piece into a rough ball by pulling the dough edges down and away from the center, then into a small knot at the bottom. Roll the dough in your hands to form a smooth ball. Evenly space the rolls in the prepared pan (they will not touch). Cover the pan with lightly greased plastic wrap, then let the rolls rise in a warm, draft-free place for 1 1/2 to 2 hours. They will puff and expand to touch one another. Place rack in center of oven and preheat to 350 degrees F.
Uncover and bake the rolls until they are deep golden brown on top, but lightly colored on the sides, 23 to 25 minutes. Remove pan from oven and let rolls cool in pan for 3 minutes. Gently transfer the rolls to a wire rack (they will be hot and delicate). Melt 2 tablespoons additional butter and brush the tops of the rolls. Serve warm or at room temperature.