1.Heat oven to 400°. Lightly grease a 9-inch square baking dish and set aside.
2.Peel plantains, cut in half, and slice each half into 3 thin slices. Heat oil in a large skillet and fry plantain slices until soft and browning around edges. Set aside.
3.In a separate skillet set over medium-high heat, add beef, sofrito, tomato sauce, sazón, and spices. Brown seasoned beef completely, stirring continually, and then set aside.
4.Line bottom of prepared baking dish with strips of plantains, spread half of reserved seasoned beef evenly over top and sprinkle with half of the cheese. Repeat layers of plantains, beef, cheese, and finish with plantains. Pour beaten egg as evenly as you can over the top layer of plantain.
5.Bake until egg is cooked and cheese is melted, about 30 minutes. Serve warm.