Tonight for dinner, I made herb and goat cheese stuffed chicken breasts. The recipe I used called for flat-leaf parsley, but I had curley on-hand. While I was cutting my herbs, I thought to myself, "what is the difference between flat-leaf and curly-leaf parsley?" Of course, there are the obvious physical differences. I took a small bite of the parsley leaf, but didn't taste a difference in flavor. The texture is different. I find curly parsley to be more gritty and coarse than flat leaf. I continued to make my herbed goat cheese and decided I would do research later.
So, here I am - minutes after completing my "research," which I place in quotes because it was far from extensive. My quick internet search showed me that many people can distinguish a taste in flavor between the two parsleys and believe that flat leaf holds more. In addition, curly is used traditionally as garnish while flat-leaf is used for cooking.
I didn't perform a scientific experiment by tasting the curly, taking notes, cleansing my palate, and repeating with the flat-leaf, but I've come to a conclusion that will work for me. I prefer flat-leaf strictly based on the texture. So, if I am using the parsley to mix into something like goat cheese (or another thick, creamy dip), curly will do the trick. If I think the flavor is weak, I can always add more. Otherwise, I'm going to typically keep flat-leaf on-hand from now on.
PS - I mixed mint and parsley into the goat cheese. The mint had a strong flavor after the chicken cooked, which I liked. However, if mint isn't your thing, or if you just want to try something different, I think that chives, sage, or taragon would also work well, with or without the parsley. While I was mixing, I also thought about how delicious my goat cheese mixture would be on some crostini. To make a goat cheese spread, I would cut the flavor of the goat cheese with a little lemon juice and use mild herbs.