Combine Monterey Jack, White Cheddar, and Parmesan cheese in a medium bowl. Add the cornstarch and toss gently with your hands.
Over medium heat, add the White Cooking Wine to a large, heavy-bottomed deep pan.
Whisk in the garlic and bring the cooking wine to a bubble.
Add the spinach and artichoke hearts and mix well. Let the mixture come back up to a bubble and cook for 1 minute.
Add in the cheese in 4 additions, whisking until combined after each addition.
Once the fondue is silky smooth, transfer the pan to your serving table, surrounded by all of your favorite dippers. Alternatively, you can pour the cheese fondue into a fondue pot set to low and enjoy!
Notes
I strongly urge you to shred your cheese for this recipe. Pre-shredded cheese has other additives that may alter the silky smooth texture of the cheese fondue.