The Rookie Cook

Heavy cream is not the same as whole milk. Also called “heavy whipping cream,” a heavy cream has between 36% to 40% milk fat, and will double in volume when you whip it—whip it good.

That having been said, in a pinch you can indeed substitute whole milk for heavy cream, but to be honest I rarely have whole milk in my refrigerator, so that’s not a substitute I’m likely to use. Milk and butter, on the other hand, are usually available. To make 1 cup of heavy cream, you’ll need 3/4 cup milk
1/3 cup butter melted and cooled. Combine and add to recipe.

If you regularly keep half and half around for use in your coffee, you can try that. Blended cottage cheese can simulate the thickening effect. When you’re making a soup that calls for heavy cream, you can add the equivalent amount of milk, then just before the soup’s done cooking, remove a cup or so of soup from the pot and beat in an egg yolk. Once the egg yolk is mixed in thoroughly, add the liquid back to the soup and finish cooking.