In a large bowl, whisk together the parsley, garlic, parmesan and za'atar. Taste and add more za'atar as you prefer.
Add in the olive oil and mix. You want the mixture to be a thick paste. Add more olive oil as needed to keep the mixture thick, but still spreadable.
If you are grilling this on toast, put a non-stick skillet on medium heat.
Take a slice of bread and generously spread a thick layer of the za'atar spread onto the bread.
Grill the bread face down in the pan for 1-2 minutes or until the parmesan has turned golden brown and crispy. Flip and let the other side of the toast get crispy.
Repeat as needed with the other bread slices, then serve!