Preheat the oven to 400°F. Prepare the acorn squash by cutting it in half horizontally and scooping out the seeds. Brush all sides with oil and season with ½ teaspoon salt and ½ teaspoon pepper. Line a small sheet pan with parchment paper and place the squash cut side down. Bake until the flesh is soft and can be easily pierced with a fork, about 30 minutes.

While the squash is roasting, heat a medium skillet to medium-high heat and add the walnuts. Dry toast them for about 2-3 minutes until browned and toasty.

To the same skillet, add the 2 tablespoons of sun-dried tomato oil. Add onions and saute until soft and translucent, about 5 minutes. Add the garlic and saute another 1 minute until fragrant. Add the chickpeas and cook until warmed through, about 3 minutes. Add the spinach, sun-dried tomatoes, cumin, remaining salt, and remaining pepper. Pour the lemon juice on top and toss well to combine.

Flip the acorn squash over and spoon the filling evenly into the four squash halves. Place back in the oven for an additional 10 minutes, and serve warm.