Great weather for fondue. I have used the recipe from Jacques Pepin's
The Short-cut Cook for many years. It doesn't call for champagne, but does have a good dose of white wine in the recipe, so I don't see why you couldn't try the champers and see what happens.
Here are the ingredients (which are not copyrighted):
2 TBSP unsalted butter
2 cloves garlic, peeled and chopped
1 1/2 cups dry white wine
1/4 tsp salt
1/2 tsp freshly ground black pepper
3 packed cups shredded Swiss cheese (preferably all or part Gruyere)
Note that the recipe doesn't call for any thickener; the cheese tends to sink to the bottom and the clear liquid rises to the top, and you keep stirring it together as you dip the bread. I use part Emethaler and part Gruyere. The fondue has a cheesy, wine-forward flavor that to me, tastes like home on a cold night.