Yes, fitday.com will do that for you. I did it just the other day with a really nice date and oatmeal cake. You need to use custome foods. I made the cake, cut it in 12 and then entered all the ingredients as 12 servings. I then ate one
I couldn't work this out on Fitday. Do I have to save each item in the recipe as a custom food? I tried the Help section, but it doesn't say anything about entering recipes.
I usually enter all of the ingredients of my recipe (I go to the next day so that there are no other foods entered). Then, just run the report that tells you whether or not you are meeting RDA standards and the one for meeting your custom nutrients. You'll be able to easily note the nutritional information and then enter the recipe as a custom food. You can use what would be considered a serving size for each ingredient but I usually just keep nutritional value of the whole recipe and update the day's intake based on how much of the recipe I actually eat.