Make the fries: Preheat the oven to 425 degrees F. Cut the potatoes into thin wedges; toss with 1 tablespoon olive oil and 1/2 teaspoon chili powder on a baking sheet. Spread in a single layer and roast until golden, turning halfway through, about 30 minutes.
Meanwhile, heat the remaining 2 tablespoons olive oil in a large skillet over medium-high heat. Add the beef and the remaining 1/2 teaspoon chili powder and cook, breaking up the meat with a wooden spoon, until browned, about 5 minutes. Add the scallion whites and garlic and cook until slightly softened, about 2 minutes. Add the ketchup, brown sugar, Worcestershire sauce and 1 1/2 cups water; reduce the heat to medium and simmer until thickened slightly, about 8 minutes.
Divide the fries among plates. Top with the beef mixture, cheddar, mozzarella, scallion greens, tomatoes and pickled jalapenos.