Pierce your spaghetti squash several times with the tip of a sharp knife.
Place the spaghetti squash on a microwave-proof plate, and microwave on high for 12 minutes, stopping to check on and rotate the squash every three minutes.
Remove the squash from the microwave and let it cool until you're able to handle it comfortably.
Slice the squash in half, and use a spoon to remove the seeds.
Use a fork to shred the spaghetti squash flesh into "noodles" and transfer the noodles into a bowl.
MAKE THE SAUCE
Preheat your oven to 350°F / 180°C at this point.
Heat the olive oil over medium heat in a large heavy-bottomed skillet.
Add the onion, and cook, stirring often, until it is well-browned - about 10-15 minutes.
Add the garlic, celery, and carrots, and cook for about 5 minutes more, until the vegetables are softened.
Add the white wine and stir the contents of the pan well to lift the flavour from the bottom. Allow the wine to evaporate almost entirely.
Add the crushed tomatoes, and stir to combine well. Season with salt and pepper.
ASSEMBLE THE CASSEROLE
Add the tomato sauce to the spaghetti squash noodles, and stir to combine well.
Transfer to a 9x9 inch casserole dish.
Place in the oven, and bake for 30 minutes. The sauce should be bubbling up around the sides at this point.
Remove the casserole dish from the oven and scatter the cheeses over the top.
Return to the oven and bake for an additional 15 minutes, until the cheese is browned and bubbly on top.
Remove from the oven and let rest for 5 minutes before serving.
Nutrition values are an estimate only.
You're aiming for teeny tiny finely diced vegetables in this dish. Feel free to shred them or do the chopping in your food processor to save time.
While this recipe calls for white wine, I seldom have white wine kicking around in the colder months, but I always have a bottle of white vermouth in the liquor cabinet and use them interchangeably for cooking.
Can I make this recipe in advance? You sure can! You can prepare everything in advance and leave it in the refrigerator until you're ready to bake it.
Tip! Cook the spaghetti squash ahead of time and this recipe will come together quickly.
Can I freeze this recipe? To be honest, I don't love this recipe frozen and re-heated. I recommend you keep the leftovers in the fridge and eat them up within 3-4 days.