What type of plaster for this patch

[Burnsie1983]

Hello

So, I was changing a back box from a single to a double in an external wall.

Unfortunately the previous back box had been nailed into place and the only way to remove the back box was to smash it with a hammer and lever it out. As a result some of the plaster has come away around the new back box as shown in the picture

The main area on the left-hand side of the image is around about half a centimetre to one centimeter deep... But in some places a little deeper.

The maybe some stuff around the right hand side of the image that you can't see that is breeze block and little plaster!

Would a simple bonding agent and then some layers of lightweight plaster do the job?

Although I want it to look relatively good this is hidden under a desk so it doesn't have to be perfect

Any advice gratefully received

 

[Wayners]

Got any wood glue? 4 parts water to 1 part glue and seal area.
Box of toupret powder.
Fill.
Surface will be dry in 24h and could paint but may take a couple of days to fully dry out.

Fill a bit and hour later fill again then hour later fill again. Keep building out so done In one day.

Cling film and tape around metal face plate or remove as it will tarnish with wet filler