Rinse whole kabocha squash, cut in half, scoop out and discard seeds. Cut into wedges about 2 ounces each. Place the squash wedges into a roasting pan, single layer and drizzle with olive oil. Cover tightly and steam roast in a 350°F oven until tender, about 35 to 45 minutes.
Meanwhile, lightly toast the nori sheet on a grill or griddle, it only takes 5 seconds on each side, do not burn. When cooled, crumble into a spice grinder and add toasted sesame seeds and salt. Process until fine. Mix in pepper. Sprinkle over kabocha.