1. Preheat your oven to 400 F (200 C). Carefully cut each butternut squash in half lengthwise. Scoop out the seeds and stringy bits from the center. Lightly brush the cut sides of the squash with 1 tablespoon of olive oil, and sprinkle with a pinch of salt and pepper. Place the squash halves cut-side down on a baking sheet lined with parchment paper. This helps them cook evenly and prevents sticking.

2. Roast the butternut squash in the preheated oven for 30-40 minutes, or until the flesh is tender when pierced with a fork. The edges might start to caramelize slightly, which adds to the flavor. Once cooked, remove from the oven and let cool slightly while you prepare the filling.

3. While the squash is roasting, heat the remaining 1 tablespoon of olive oil in a large skillet over medium heat. Add the chopped yellow onion and celery. Cook, stirring occasionally, for 5-7 minutes until the vegetables have softened and the onion is translucent.

4. Add the diced apple, fresh sage, and dried thyme to the skillet with the softened aromatics. Continue to cook for another 3-5 minutes, stirring occasionally, until the apple pieces are slightly tender but still hold their shape. The kitchen will start to smell wonderfully fragrant at this point.

5. Remove the skillet from the heat. Add the cubed sourdough bread to the vegetable and apple mixture. Pour in the vegetable broth, and season with salt and black pepper. Gently toss everything together until the bread cubes are evenly coated and have absorbed some of the broth. The mixture should be moist but not soggy.

6. Once the roasted butternut squash halves are cool enough to handle, turn them cut-side up. Generously spoon the sourdough, apple, and sage filling into the hollowed-out centers of each squash half, mounding it slightly. Return the stuffed squash to the baking sheet.

7. Place the stuffed squash back into the oven and bake for an additional 15-20 minutes, or until the filling is heated through and the top is lightly golden and slightly crispy. The aroma will be incredible when it’s ready.

8. Carefully remove the stuffed butternut squash from the oven. Let it rest for a few minutes before serving. You can serve each half as an individual portion, or slice them into smaller pieces for a side dish.