AJP - It will be fine, just a little less unjunctious although if you leaving out the mozzarella then you could skip the oven stage as well, and just make the dish in a frying pan.

Make the gnocchi as per the recipe

To make the sauce - half the amount of passata, then add the cooked gnocchi directly into the sauce before the grated cheese. Just toss gently to coat/reheat the gnocchi and melt the cheese into the sauce.

If you want a crispy top then add more parmesan on the top and flash under the grill