You can make this in the Insta Pot or in a slow cooker. Just saute all of the ingredients except the milk, butter and cheese which you will add at the end just as though you made the recipe in the Insta Pot.
On the Insta Pot, select SAUTE on NORMAL setting. After one minute, add olive oil and 2 tablespoons butter. When butter melts, add chopped onion, celery and carrot. Add salt.
Cook for about 3-4 minutes, stirring vegetables to coat well. When the vegetables are starting to soften and brown, add the garlic, bay leaves, brown sugar and nutmeg. Cook for 1 minute.
After 20 minutes, preheat the oven to 400 degrees. Spread the spiralized zucchini onto a parchment lined cookie sheet. Set aside.
Taste and correct the bolognese for salt. Remove bay leaves.