Preheat the oven to 375 degrees F. Heat the olive oil in a large skillet over medium-high heat. Add the pork, 1/4 teaspoon salt and a few grinds of pepper. Cook, breaking up the pork, until slightly browned, 2 minutes. Add the garlic, mushrooms, half of the scallions and 2 tablespoons panko; cook 3 minutes. Add the tomatoes, half of the parsley and 1/3 cup water. Increase the heat to high; cook until slightly thickened, 3 minutes.
Combine the cottage cheese, 3/4 cup Mexican cheese and the remaining parsley in a bowl. Sprinkle 3 tablespoons panko in a 9-inch-square baking dish. Top with half of the squash, overlapping slightly; season with salt. Top with two-thirds of the pork sauce and the cheese mixture. Add the remaining squash; season with salt. Add the remaining 3 tablespoons panko, pork sauce and 1/2 cup Mexican cheese.
Cover with foil and bake until the cheese melts and the squash is tender, about 20 minutes. Uncover and turn on the broiler; broil until golden, 2 minutes. Top with the remaining scallions.