Preheat oven to 425°F.
Halve each butternut squash lengthwise and remove the seeds.
Place cut side up on a baking sheet.
Drizzle with 1 tbsp of olive oil and season with salt and pepper.
Grill until tender. Took me about 40 minutes for a large squash.
In a frying pan, saute sliced onions for 2 minutes. Add in chopped garlic and saute for another minute.
Finally, add mushrooms and cook till lightly caramelized. Season with salt and pepper.
When the squash is cool enough to handle, carefully scoop out the flesh into a bowl and mix in the sauteed ingredients.
Mix in dried herbs, Parmesan cheese and half of the cheddar.
Place the squash in a baking dish or alternatively, you can bake the squash in the squash shell too.
Top with the mozzarella and remaining cheddar. If you are using bacon, add that in too.
Bake for another 15 minutes.
Once out of the oven, top with basil.