I would think it would be the liquid since there is 2 lbs. of powdered sugar and the only other liquid is the water which is only 1/2 to 1/3 cup and only 1 tsp. of almond extract. But I would be sure to add the water last and start out with 1/4 cup just be sure sure it's not too wet and then add more if needed. AND, if you try the liquid and it is too wet, you can omit all the water and I don't think it would make too much of a difference.
I'm no expert, but that is what I would use.
Hope it turns out. Let us know. I will be wondering.
Take care!
Karen