Some sort of butter-olive oil-white wine-lemon direction…..

2 easy tasty options. You could add in fresh basil or chives to either.

Make a simple brown butter.

Make a beurre blanc.

I bet au poivre sauce would be delicious on portabella ravioli.

Parmesan Cream Sauce.

Brown butter, pasta water, and Parmigiano Reggiano or Pecorino cheese

Is sage butter sauce too obvious a suggestion?

Garlic butter with basil and toasted pine nuts sounds good to me, maybe finished with a balsamic reduction.

Also, I learned something new today. I've never noticed the word portabella before, so I assumed you spelled portabello wrong. Didn't realize that smaller, less mature portabello mushrooms have a different name.

Romesco

B-1 83 said:

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Some sort of butter-olive oil-white wine-lemon direction…..

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looks like you are most of the way towards a piccata