You can mold a recess, deep enough to “look” similar, but in that particular instance there is just an outer ring, an inner ring. This teardown shows how the flat cap just snaps in place.
If you wanted to mold it as a single part, you would need to have ribs between the two reducing the floating effect (ex every 90 degrees) to hold the two together and you might run into trouble with how the part is gated (as well as potential stresses where the two get held together, as it wouldn’t be terribly sturdy.