Preheat the oven to 350ºF.

Trim the scallions, then dice them to yield ½ cup. Dice the zucchini. Peel and mince the garlic.

Slice the plantains in half lengthwise. On a baking sheet, toss the plantains with a drizzle of oil, then bake for 10 minutes.

While the plantains cook, heat a drizzle of vegetable oil in a large sauté pan over medium-high heat. Add the scallions and garlic and cook, stirring, until fragrant, 1-2 minutes. Add ground beef and cook, breaking up the meat, until browned and cooked through, 7-10 minutes. Season with salt and pepper.

While the beef cooks, in a separate large sauté pan, heat another drizzle of vegetable oil over medium-high heat. Add the zucchini and spinach and cook, stirring occasionally, until the zucchini is browned and the spinach is wilted, about 5 minutes. Season with salt and pepper.

Stir the cooked rice into the pan with the sautéed zucchini and spinach.

In a large baking dish, assemble the pastelón: Layer the bottom of the baking dish with half of the cooked plantains. In even layers, add half of the rice and veggie mixture, then half the ground beef mixture. Repeat with the remaining plantains, rice and veggies, and ground beef. Sprinkle the cheese over top.

Bake until everything is warmed through and the cheese is browned and melted, 30-40 minutes. Let cool for 15 minutes before serving.