It may be that Mr. Price has told a lie on page 58 of the Treasury. I don't know for sure, but here's what he says in the preface to the recipe:
We have arrived at this very acceptable substitute for the French cheese though trial and error . . .
The substitute the Price's arrived at through trial and error is cottage cheese. How much trial and how much error did they go through? Even in the 50s in California in L.A. surely there was a cheese shop? Surely there was a supplier?
Many contemporary Coeur a la creme recipes call for cream cheese or cottage cheese. I think if one were to try to be authentic, then using Neufchatel or creme blanc or both would be the way to go. I like a little bite to my creamed cheeses so I'd whip some tart goat cheese in there too.
I'm giving Price a little guff here because I hold his taste in high esteem and my inner snob is nose to the ceiling over using crappy cottage cheese in this recipe. But perhaps I am just being a snob. It's a calling.
Price's recipe calls for lining heart shaped wicker baskets with cheesecloth but we live in a modern culinary utopia here in 2015 and you can buy awesome coeur de creme molds online.