This is a very satisfying dish, so portions of ⅓rd size are adequate as main course. You could also serve 4 portions as an accompaniment to meat of your choice.
If the mushroom sauce seems too thick, you can thin it out with 1-2 tbsp almond or coconut milk.
Tastes even better when re-heated next day.
Metric Kitchen Scales are essential for accurate measurement of ingredients. They're easy to use, inexpensive and take up very little space.
THESE are the ones I use (U.S. option
HERE).