Place the cheese and cornstarch in a grill-safe bowl (preferably cast iron).

Pour the evaporated milk over the cheese.

Place on a hot grill and stir constantly until creamy and smooth, about 3-4 minutes. If it's too thick, stir in more evaporated milk. If it's too thin, stir in more cheese/cornstarch.

Spray both sides of the bread slices with olive oil spray or butter spray and sprinkle with garlic salt to taste.

Place on a grill pan and place on the grill while fondue melts.

Watch the bread closely; when the first side toasts (about 2 minutes), flip and toast the other side.

Serve the cheese dip with grilled bread for dipping.