Now. You can lower the syns in this by swapping out the beer for stock, but honestly you're doing yourself a disservice. The beer adds a lot of the taste, but it isn't essential. For the sake of a couple of syns, you'll get a great side.
We found this recipe in an Italian cookbook by a chap called Gennaro. We adapted it slightly, but full credit to the guy who looks the double of Paul's dad on the front cover. You can pick up an ecopy here.
This makes enough for four decent servings as a side dish, but we had it between the two of us because: obesity.
1kg or so of potatoes, peeled
200ml of good lager - I used Brewdog's Lost Lager but any will do - around 6 syns
1 tbsp of olive oil (6 syns)
salt and pepper
2 large onions
200g of bacon - you can buy medallions and cut them up if you like, but we just used bacon lardons and didn't syn them because we're not frightened of a bit of redundant fat, unless it's Paul's mother
80g of light extra mature cheddar (1 person's healthy extra, so fuck it, I'd be minded not to count it, but that's your choice to make) (or, do as we did, and double the cheese because you're a greedy heifer)
put the oven onto 200 degrees
using your mandolin or a knife, thinly slice the potatoes and onions
throw the potatoes into a large bowl, add the beer, oil and lots of salt and pepper
line the bottom of an overproof dish with sliced tatties, onions, few cubes of bacon and some of the grated cheese
layer over and over and press down damn hard with your hand as you go, covering the top with more grated cheese
pour over the beer mixture, give it another press down and cover in foil
bake for an hour, then remove the foil and cook for another 30 minute