Preheat oven to 425°. Cut squash in half and remove seeds. Drizzle both halves with olive oil and sprinkle with salt.
Place face-down onto a parchment-lined baking sheet and bake for 35-45 minutes, or until cooked through.
Stir in diced apple and continue to cook for 3-4 minutes.
Mix in kale, pecans, pumpkin seeds, sage, salt, pepper, and nutmeg. Cook for 1-2 minutes to heat everything up. Turn off the heat and stir in lemon juice.
To Store: Keep leftovers in an airtight container in the refrigerator for up to 5 days.
To Freeze: Seal the squash and filling separately in freezer-safe, airtight containers and freeze for up to 3 months.