answer:Usually it won’t work. Sometimes you can substitute skim evaporated milk. Also, sometimes you can use half and half or even whole milk, but skim has so much less fat that in many things it will make what you are cooking taste and actually be watery. You are more likely to get away with that sort of subtitution in cooking, but when baking (meaning baking sweets) the chemical combination of ingedients matters a lot. With creamed spinach I think you could try your recipe using some evaporated skim milk and some half and half instead of cream and cut the calories by half maybe? Or, just use half and half instead of the cream, still cuts some calories. Why not just eat plain spinach?