Not made this for a while but it is lovely - I use a tbsp of flavoured syrup in mine instead of the vanilla - Put the condensed milk, cream and vanilla into a large bowl. Beat with an electric whisk until thick and quite stiff, a bit like clotted cream. Scrape into a freezer container or a large loaf tin, cover with cling film and freeze until solid.
Dark Chocolate Ice Cream Used milk chocolate. Froze a cup of the custard, then scraped back into the rest of the custard before adding to an already-running ice cream maker. Doesn't need alcohol; it doesn't go rock solid. Flavour is very nice.