Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine peeled and diced butternut squash with sliced apples. Give them a gentle stir.

Sprinkle brown sugar, ground cinnamon, ground nutmeg, and salt over the squash and apple mixture. Toss everything together.

Drizzle lemon juice over the mixture and toss gently to combine.

Transfer the mixture into a greased 9x13 inch baking dish, spreading it evenly.

In a small bowl, combine melted butter with granola or oats, stirring until well coated. Mix in chopped nuts if desired.

Evenly distribute the granola mixture over the top of your squash and apple layer.

Cover the dish with aluminum foil and bake for 25 minutes.

After 25 minutes, remove the foil and continue baking for 15-20 minutes until the topping is golden brown.

Allow to cool slightly before serving.