In a medium pot, heat the oil over medium heat. Add the garlic, onion, bell pepper and jalapeño; cook, stirring, until softened, about 5 minutes. Increase the heat to medium high and stir in the beef and cook until cooked through, about 5 minutes; drain. Stir in the chili powder, oregano and salt. Add the tomato puree and bring to a boil. Add the beans and cook until warmed through, about 5 minutes.
Preheat the oven to 375º and place the chips in an 8-inch pie plate. Spoon the chili over the chips and top with the cheddar and Monterey cheese. Bake, uncovered, until the cheese is melted, about 5 minutes. To serve, scatter over some scallions.