You can purchase a block of paneer at an Indian grocery store or easily make it at home to add to this delicious curry. If neither of these options is plausible for you, there are also a few substitutes.  You could use Mexican queso or queso fresco, mild feta (in a block), or extra firm tofu. Paneer is referred to as an Indian cottage cheese and while the flavor may be similar to cottage cheese, the texture is not the same and will not work for this recipe.