Yes! The reason for this is salt works as a flavor enhancer. It doesn't add a salty flavor to the condensed milk brownies; rather it brings out the sweet flavors. Kosher salt is what I typically use because the flakes are bigger than sea salt. It's also iodine-free and doesn't contain any other metals either, making it preferable to table salt and purer for baking. If you use table salt instead, remember it's finer-grained so it takes up less space when being measured. Rather than using ½ teaspoon of kosher salt you should use a third less if using table salt because of this.