Is microwave considered cooking in regards to bishul akum?

Most poskim are of the opinion that a microwave is considered cooking in regards to bishul akum.

It is important to note that only food which is fit to serve at a fancy meal is subject to bishul akum, and in most cases, food cooked in a microwave would not classify as such.

Also, only cooking food is prohibited, but it is permissible for a non-jew to reheat food that was already cooked by a jew. As such, reheating food in a microwave is permissible.

שבות יצחק (ח”ו עמ’ סא) בשם הגריש”א, שו”ת שבט הלוי (ח”ח סי’ קפה), שו”ת תשובות והנהגות (ח”ה סי’ רמט אות ב), שו”ת מציון תצא תורה (אות רעו) מר’ אביגדור נבנצל, אוצר הלכות בישולי עכו”ם (פ”ב הע’ ל) בשם הגרשז”א וגרי”י פישר וגר”ד פיינשטיין