nothing beats a traybake

Us Norn Iron folk are partial to a traybake. In fact, I think Northern Ireland is probably the traybake capital of the world:

Chocolate mint slice (as seen here, made by me today)
Fifteens
Lemon squares
Malteser squares
Peanut butter squares

Lots of goodies in the shape of squares :)

My gran used to make traybakes with ovaltine in them. Anyone a recipe for that? Or ever tried it before?