Removing walls and creating half height walls

[TwilightStar91]

How do you create a wall at the end of counters as seen in plans today? The wall (square) must be as wide as the counter top, therefore, current walls don't suffice. Would you just create a really small room? And how do you place cupboards inside that wall so that it is floor to ceiling, plaster on three sides and hollow with cupboard doors?

Cheers in advance :)