I brushed glue inside both of the dadoes and then clamped it together to dry.
Here is a view unclamped and with a bit of face sanding to clean it up. I forgot to take a picture after the final sanding, but basically rounded over the edges a bit and thinned the thickness a bit on the 4 ends.
I put three or four coats of spray lacquer and hand rubbed to a nice satin finish. Here is a test hanging on the wall before shipping.
Happy to report that the customer said it exceeded her expectations. That is a great thing to hear!
-- Kevin, Blue Springs, MO