Could Sour Cream be replaced with Greek Yoghurt?

I do this all the time! Believe it or not they both have roughly the same diacetyl content (the compound that gives sour cream that buttery flavor) but the Greek yogurt will taste a little “drier” due to the acetaldehyde commonly found in most Greek yogurt formulations. Consider sweetening with a little honey to balance it out.

Hi Patti! I haven't tried that, but imagine it would work. Just opt for whole-milk yogurt if possible, so the caramel still has some richness.

Don't see why not.
Other possible substitutes for sour cream - creme fraiche, cottage cheese blended with some whole milk or buttermilk.