I’m working on a new pastry filling, consisting of cream, butter and sugar - but I’d like it to not perish if sat at room temp for several hours. I’m wondering if there’s a golden rule or ideally a formula for working out what ratio of sugar and fat to cream I need to keep it from spoiling while out of the fridge. I know a 1:1 ganache is fine, which I geuss is roughly 2 parts cream to 1 part sugar and 1 part fat. I’d like to keep the sugar at about 1/3 of the overall proportions, I find that’s optimal sweetness. Ideally it should be sent to a lab but I’m not at that stage yet.