So, can you substitute cream cheese for heavy cream? Yes, but only if you are willing to adjust your expectations and your recipe. It’s not a perfect swap; it’s a “I’m-out-of-options-and-I-refuse-to-put-on-shoes” swap. Treat it like using a flip-flop to hammer a nail: it might work once, but you’ll feel the difference immediately.
If your goal is a light, airy, or silky result, just sigh, put on your real pants, and go buy the heavy cream. Your future self, eating a perfectly smooth sauce, will send you a thank-you note. But if you’re making a hearty, rustic dish that can handle a little attitude, go ahead and thin out that cream cheese. Just don’t tell the heavy cream—it’ll get jealous.