Thanks to everyone for all the advise. However, I have since solved my problem. I used MeshCAM Art to carve the dish.
I simply drew a 3" diameter circle, and colored it black. Imported the bitmap image into MeshCAM Art, and used the Shape Editor with the following specifications:
Shape: Round
Angle: 33 degrees
Starting Depth: .01"
Height Limit: No Limit
Subtract.
Then generated the tool path, using a 1/4" endmill as the roughing tool, and a 1/8" endmill as the finishing tool.
The result was a dish with a depth of .556" at it's deepest point (center of circle), which feathered out to zero around it's perimeter. Works for me, this cut was used to create a "funnel" which is used to guide a pinball into it's return trough slot. I was already aware that MeshCAM Art could handle it. I was simply curious to learn the math involved in manually coding such a cut. I did attempt to use the Newfangled Wizard for a circular pocket. However, there do not appear to be fields available to control the cutting depth other than a flat bottom cut. I did try editing the resulting g code, to plunge the Z deeper between each pass. Which did a pretty fair job. But it was a spiral cut, which resulted in a "threaded" spiral, in the surface. As opposed to the desired smooth slope I was looking for.
Again, THANKS everyone!
-Michael