Preheat oven to 400 degrees Fahrenheit.
Cut spaghetti squash in half lengthwise. Scoop out the seeds with a spoon. Brush insides with olive oil. Place face down on a pan with sides, and cook for 30-45 minutes, or until golden brown on outside and soft to the touch.
Once cooked, place aside and allow spaghetti squash to cool.
While spaghetti squash is cooking, heat a large skillet over medium heat. Add in chopped brats, and chopped onion and sauté for 7-10 minutes. Add the mushrooms and sauté for another 5 minutes. Transfer everything from the skillet to a large casserole dish, leaving the fat.
Sauté kale in the fat for 5 minutes.
Make the cheesy garlic sauce. To make the sauce, combine all the sauce ingredients into a blender and blend on high until creamy consistency is achieved. May need to add some water to make creamier.
Once the squash has cooled, use a fork to remove the strands and transfer to the large casserole dish and mix with the brats, onion and mushrooms.
Add sauce to the casserole dish and mix.
Add kale and sliced sun-dried tomatoes and mix some more.
Bake at 400 degrees for 20-30 minutes, until edges are golden brown.
Serve and enjoy!