Preheat oven to 350°F.
In a small bowl, combine cream cheese, sour cream, garlic powder, and oregano. Spread cream cheese mixture into a 9-inch pie plate. Spread pizza sauce evenly over the cream cheese mixture. Arrange the pepperoni, onion and green bell pepper over the sauce.
Bake 10 minutes. Remove from oven and sprinkle cheese on top. Return to oven and bake until cheese is melted and bubbly.