Make Pureed Winter Squash. If using frozen squash, cook according to package directions.
Meanwhile, roast peppers: Place over a gas flame and roast, turning as needed, until blackened on all sides, 2 to 3 minutes. (Alternatively, broil peppers on a baking sheet, turning from time to time, until blackened on all sides, 4 to 8 minutes.) Transfer to a paper bag and seal or place in a medium bowl and cover with plastic wrap. Let stand 10 minutes.
Mix the squash puree, cornmeal, pineapple juice concentrate, butter, cumin, oregano and salt in a large bowl until smooth.
Peel the peppers and rinse. A few blackened specks left on them will be fine. Make a long incision down one side of each pepper. Gently pry peppers open, then scoop out seeds and membranes, taking care not to tear the soft skin.
Carefully spoon about 1/3 cup squash filling into each pepper, followed by 2 tablespoons queso blanco (or Monterey Jack). Gently fold peppers closed.
Preheat oven to 350 degrees F. Coat a baking sheet with cooking spray. Place flour, egg and breadcrumbs in 3 separate shallow dishes. Dredge each pepper in flour, roll in egg, then coat with breadcrumbs. Heat oil in a large nonstick skillet over medium-high heat. Add the peppers and cook until lightly browned all over, 4 to 6 minutes. Transfer to the prepared baking sheet.
Bake the peppers until the cheese has melted and the filling is hot, about 20 minutes. Let cool for 5 minutes. Serve with a dollop of sour cream (or yogurt).