Yep you can use lots of recipe base sachets in the SC, they're fantastic, I make beef stroganoff using them and it's wonderful. Yep follow the instructions on the recipe pack, and you need to use less liquid not more. So use half to 3/4 of the amount that it tells you. If it's still too thin when it's finished cooking, thicken it with a little cornflour mixed with water. As for how long, a casserole like that between 7-8 or 8-10 hours, depends on your SC itself, if you're going to be home all day keep an eye on it, may be done sooner than you think.