Wide board oak ledge door.

[biffvernon]

Oh yes, I forgot Penners' suggestion in his drawing. That's probably the simplest way. It you chamfer the edges the join ends up V-shaped. Why make the crack deliberately bigger? It makes it look deliberate. Without this the crack will probably be tight in some places and open in others. That inconsistency can look messy. If you happen to have the one of those old molding planes that cuts a tight V next to a curved edge you get a 'beaded chamfer', a common and traditional form of decorative molding for door board edges.

As in the bottom side of the lower drawing:

 

[Penners]

If you chamfer the edges the join ends up V-shaped. Why make the crack deliberately bigger? It makes it look deliberate.

Good point.