https://beerandbrewing.com/make-your-best-sweet-milk-stout/
The grist is actually pretty simple: it’s nine pounds (4.8 kg) of Maris Otter, one pound (454 g) of pale chocolate malt (215L), and half a pound (227 g) of Dehusked Carafa III. The Maris will add a good English bready background, the pale chocolate adds some roasty coffee and chocolate notes, and the Carafa III stands in for roasted barley or Black Patent as a color adjuster and adds a mild chocolate-covered-espresso-bean roast flavor (instead of the acrid, sharp roast of the other black malts). To this, we add half a pound (227 g) of lactose. I’ve tried the recipe without it, mashing high to increase the long-chain sugars and/or adding a bunch of crystal malt to get unfermentables, but none seem to turn out quite right. This light touch of lactose, though, seems to do the trick. You’ll end up with a beer that’s just about 5.5 percent ABV, jet black, and nicely (but subtly) roasty and sweet, just like I like my coffee.
English hop varieties such as Fuggles, East Kent Goldings, or Columbia are appropriate