I have replaced the fridge-freezer in the kitchen. Here's how it looked after we removed the overhead cabinet.
My plan is as follows:
1. Buy plaster.
2. Mix the plaster with water in a bucket.
3. Moisten the wall a little with a wet sponge.
4. Apply with a putty knife.
Questions:
1. Is this an OK plan?
2. Which plaster can you recommend? Some say it's only for small holes and not to be used over wood. Here I think there are wooden walls.
Unscrew the electrical outlet first.
You'll have easier access with the wide putty knife and reduce the risk of getting damp mortar in it.
It might be a good idea to remove the fuse as well...
I like casco wallfiller, but there is probably no significant difference between different brands, plaster is not a unique product directly.
When repairing such deep damages, it's easiest to do it in two rounds and let it dry in between.