Put in the false back, and put a cabinet door on it. Using it for pans and the like is going to cause you to have to wash them before you use them as they'll end up dusty.

Why is it so abnormally deep in the first place? Standard cabinet depth is 24''.

Yes, recheck those dimensions, wall oven are typically 24 deep. If it was the refrigerator, it would make more sense but not the oven.

Mine is deep and I love the extra space to store large items.

Mine is waaay deep too. I have a plan to remove my wall oven, put 2 ovens side by side under my countertop stove and just open up where the wall Oven is now, and put a counter top and a few open shelves for everyday items so there's no unnecessary washing. My house was built in 1969 and I love it, however, these builders wasted so much space it's not even funny. The opposite of my wall oven is my bedroom closet and I won't demo 2 areas if its not within my budget or needs.

I have AT LEAST two times the space as home sweet home. Frustrating but also a blessing. You have more options.