We made it in school. We made a very small batch with the tomme d'auvergne cheese, which was stupid expensive. Then we made batches with cheddar cheese curds (like used in poutine) and with a mixture of a good gruyere and fresh mozzarella (has to be the fresh mozzarella, it is a different animal than the older, firm mozzarella.)
The saddest part of using the tomme d'auvergne is you are supposed to peel the rind off for the recipe and the rind in a soft, semi-fresh cheese is where a huge portion of the flavor comes from. The cheddar cheese curd version was okay, the gruyere and fresh mozzarella mixture was best, closest to the recipe but affordable and available for most uses. You subbed 75% gruyere and 25% fresh mozzarella for that version. The cheddar cheese curd version was a 1:1 substitute. Cheddar cheese curds are fresh also, they are not an aged cheese so that sub works well. If I was going to use the cheddar cheese curds, for about 3 pounds of potatoes, I'd take about 1/2 cup of mushrooms, chopped large, and 1/4 cup of toasted (to release the nutty flavor) walnuts and put it in a sachet and boil in the water I was going to cook the potatoes in, for about 10 minutes, then remove the sachet and cook the potatoes in that water. It would add some of the umami that is in the recipe cheese (and in the gruyere) but is missing in the cheddar cheese curds.
Also, when you drain the cooked potatoes (I'd save the liquid you drain off for the soup container in the freezer), spread out the potatoes around the edge of the colander and let them steam, stir them roughly to break them up a few times and let them steam each time until they no longer steam. That helps remove some of the trapped water inside the potato pieces, giving you more potato flavor and letting the other ingredients in the dish cling together better. That really goes for any time you boil potatoes in my opinion.
The saddest part of using the tomme d'auvergne is you are supposed to peel the rind off for the recipe and the rind in a soft, semi-fresh cheese is where a huge portion of the flavor comes from. The cheddar cheese curd version was okay, the gruyere and fresh mozzarella mixture was best, closest to the recipe but affordable and available for most uses. You subbed 75% gruyere and 25% fresh mozzarella for that version. The cheddar cheese curd version was a 1:1 substitute. Cheddar cheese curds are fresh also, they are not an aged cheese so that sub works well. If I was going to use the cheddar cheese curds, for about 3 pounds of potatoes, I'd take about 1/2 cup of mushrooms, chopped large, and 1/4 cup of toasted (to release the nutty flavor) walnuts and put it in a sachet and boil in the water I was going to cook the potatoes in, for about 10 minutes, then remove the sachet and cook the potatoes in that water. It would add some of the umami that is in the recipe cheese (and in the gruyere) but is missing in the cheddar cheese curds.
Also, when you drain the cooked potatoes (I'd save the liquid you drain off for the soup container in the freezer), spread out the potatoes around the edge of the colander and let them steam, stir them roughly to break them up a few times and let them steam each time until they no longer steam. That helps remove some of the trapped water inside the potato pieces, giving you more potato flavor and letting the other ingredients in the dish cling together better. That really goes for any time you boil potatoes in my opinion.