Depending on whether that's one-off or something to repeat, a properly shaped bit with "negative curve" will be the most efficient (single pass) and neat (no grooves from multiple passes) solution.
I don't have a photo of the tool in question, but the one in the middle has some similar properties - it was used to create undercuts (-30 degrees edges) and its side edge curves in a way similar to what you'd need to obtain. So, simply grind a bit to the correct radius and pass it once (or in enough approaches as not to break the bit).
Alternatively, if you either don't grind your own bits or are unwilling to use up a new blank for something you'll use once, use a round tip bit, and have the CAM software calculate tracks for the right curve, then make it pass enough times so that the lines will be possible to remove with sandpaper.
Note you don't need many bits for different curves. Make one of fairly large curve and route it along the right circle (radius = bit radius - fillet radius) in the Z-axis , and it will be much more graceful to smooth out than created with a round tip.