Place both the shredded Gruyere and Swiss cheeses in a gallon-size resealable bag with the cornstarch and shake until evenly coated.In a stovetop-safe fondue pot (or in a regular saucepan or electric fondue pot), add the chicken broth, lemon juice, and garlic and bring to a simmer. Reduce the heat to medium-low. Add the cheese, a small handful at a time, stirring constantly, but not briskly. It works best to use a wooden spoon and and stir in an S-shaped motion, making sure to scrape the bottom of the pot so it doesn’t burn.Once the cheese is melted and begins to just barely simmer, add the remaining spices and move it immediately to the table on the fondue stand with the sterno flame below. It should be the consistency of warm honey. Add more or less cheese for perfect consistency and additional salt and pepper to taste if needed.Serve with your favorite fondue dippers: steamed broccoli and/or cauliflower, carrots, apples, chicken sausages, bread (and more bread!), lightly sauteed mushrooms, tender potatoes – the options are endless! Don’t forget if you drop your food into the fondue pot, lean over and give your neighbor a kiss!