Remember to keep an eye on the oil temperature; I think after I got the oil hot I started cooking with about 7 (out of 10), but had to notch it up a bit after every batch (the oil cools off in use?), ending with about 8 1/2 on fourth one, (with three donuts in each). I made accidentally about double the recipe; you can see if the batter doesn't turn up brown fast, you need to turn the heat up a bit... of course it all depends on what size of dish you're cooking in...

oh, and 2 dl is a bit less than a cup, cup being 2,34 dl.