Grate all cheeses and add to a medium bowl. Add 1 Tbsp cornstarch and toss together until evenly coated.
In a stove-safe fondue pot or a large saucepan, add ½ cup white wine, 1 clove minced garlic, and 1 Tbsp lemon juice to a simmer over medium-low heat. Once bubbles begin to form across the liquid, add the cheese a sprinkle at a time, stirring well between each to ensure a smooth and cohesive fondue. The slower and more patient you are the better incorporated and smoother the fondue will be.
Once smooth and melted, add in the 1 Tbsp honey mustard, and ⅛ tsp nutmeg. Season more to taste as desired.
Transfer from the stove to fondue pot as needed, or place on warmer plate. Arrange assortment of fondue dippers within easy reach and provide fondue forks or wooden skewers. Enjoy warm!