Oh Donna!
Keep a squirty bottle full of water and/or a noisy saucepan & wooden spoon on the surface so you can pick it up as soon as you step into the kitchen. If you find an intruder - let him have it!

Full on, tons of water, lots of noise, shout at it, psss psss psss at it, clap your hands, slam the door etc etc. I'd have no problems with ayone doing any of the above to my cats (as long as they didn't scare it witless into the traffic etc) .... it should shoo them off in short order. To quote Corporal Jones -
They don't like it up 'em