Heat the olive oil and butter in a large stockpot over medium heat, about 2 minutes. Add the onion and garlic and saute until tender, 5 to 7 minutes. Add the quinoa and corn and saute for 3 more minutes. Add the stock, heavy cream, potatoes and Old Bay. Increase the heat to high and bring the mixture to a boil, then reduce the heat to medium low and simmer, uncovered, until the quinoa and potatoes are tender, about 30 minutes.
Meanwhile, cut the bacon into small pieces and add to a medium skillet over medium heat. Cook until browned and crisp, about 4 minutes, stirring constantly. Remove to a paper towel¿lined plate to drain. Set aside.
Add the shrimp to the chowder and cook until they are pink and opaque, 2 to 3 minutes. Just before serving, add the parsley, scallions and bacon.