New Potato Gratin

When I first learned to make a potato gratin it was with russet potatoes. A few, some may call "progressive", chefs used yukon gold potatoes(or similar varieties), but mostly it was all about the potatoes with a high amylose to amylopectin ratio(more on these starches here). I like both approaches, but here is a recipe using freshly dug red new potatoes. They aren't like russets or yukon golds. The result is a soft and creamy gratin throughout.
Ingredients:
1250g new potatoes
284g cream
12g thyme
4g fresh bay
38g shallot, sliced
16g garlic, smashed
1g black pepper corn
5g +7g salt
76g Berkswell, grated
140g Pyrenees Brebis, grated
30g water, depending on evaporation (see method)
Method:
Bring the cream, thyme, bay, shallots, peppercorn, and garlic to a boil. Keep the infusion on very low heat for 30 minutes. Pass the cream through a fine strainer, but keep whatever doesn't pass through in the strainer, you will need it soon(don't let it drip all over the place). Weigh the cream and subtract this weight from 290g. Add the difference, in grams of water, to a separate container and then pour the water over the leftovers still in the strainer, being sure to mix this water with the already passed cream. I know this seems like a lot, but I(and I think you) want this extra water during the cooking process and pouring it over the aromatics in the strainer gets out any little bits of flavor or cream you would have otherwise left behind(I'm positive no one wants to throw away free flavor). Press all of the liquid out of the strainer that you can, and then discard anything that doesn't go through. Add 5g of salt to the cream.

Work quickly at this point or the potatoes will start to brown. Peel and slice the potatoes 2mm thick. Once sliced, do not place the potatoes in water. Place the potatoes into a large bowl and toss with 7g salt. Coat the bottom of the a baking pan with infused cream and shingle the potatoes in one uniform layer over the cream. You want to leave behind any liquid or salt that runs off of the potatoes during this process(i.e. the bowl should have a few tablespoons of brine left when you are done).
Coat the potatoes with cream and a small amount of both cheeses. Repeat until you run out of potatoes. Any left over cream or cheese should be applied to the top layer.Bake uncovered at 300F for around 3.5 hours, until the top is dark brown and enough moisture has evaporated so that the potatoes are not swimming in cream.

The cross-section

The plate it up

Lamb rack, flap, and sausage with Berkswell and Pyrenees Brebis new potato gratin, fava bean and morel mushroom stew, mustard greens, and lamb jus

If you keep baking until fat starts to collect on top of the gratin you have evaporated too much water, broken the cream, and separated the cheeses. You want to bake it slow for a long time, but not too long. Adding water back to the cream after infusing should prevent this from happening, but if it starts to get fatty take it out, unless it isn't brown, then you should broil that thing hard and fast before removing from the heat. Making this days in advance and letting it chill completely will allow you to cut uniform, accurate portions. It tastes great freshly baked, but it doesn't look pretty out of the pan it was baked in. The cheeses I used are expensive, the Berkswell especially. I think it was worth it, but I can't be sure until I do a side by side, blind, tasting. I just used them because they are both delicious sheep's milk cheeses and I was serving it with various delicious sheep parts. It made sense at the time.

Hugely,

Adam