Wall cupboards onto plasterboard lining

Hi - I've fited several kitchens over the years as successful DIY projects - but always had solid brick to attach the wall cupboard brackets.

I'm now replacing my son's kitchen and this is plasterboard lined, dot and dab onto blockwork. The "cavity" between plasterboard and blockwork is approximately 15mm.

The wall cupboard fixings from the old units appeared to screw directly through the plasterboard and into the blockwork with no apparent wall plugs - a strange shallow spiral thread....

Wall cupboards onto plasterboard lining