Heat the oil in a medium skillet over medium heat. Add the onion, garlic, and jalapeño, and cook until softened, about 3-4 minutes. Add the chili powder, cumin, cinnamon, and salt, and stir to combine. Add the tomato and cilantro, and cook 2-3 minutes. Stir in the chicken and sour cream, and cook until heated through.
To assemble the chimichangas, spread a few tablespoons of refried beans down the center of each tortilla. Top each tortilla with ⅙ of the chicken mixture, and ¼ cup of Monterey Jack cheese. Fold the sides of the tortilla toward the center, then roll each tortilla up into a burrito shape.
To bake the chimichangas, brush each of the chimichangas with oil and place on a greased baking sheet. Bake at 450°F for 8 minutes, then flip and bake for an additional 5-8 minutes, until golden brown.
To fry the chimichangas, heat 1-2 inches of oil to 350°F in a heavy pot or deep fryer. Secure the chimichangas with toothpicks to prevent them from opening while frying. Fry the chimichangas 1-2 at a time for 3-4 minutes, or until golden brown, flipping halfway through.
Serve the chimichangas hot with the toppings of your choice.