If you don't find any factory made component, you can always get down the do-it-yourself route.
Here is a link to set of instructions on how to make ones for Shimano PD 520/540:
The basic idea of it is to get hold of an extra pair of cleats, affix them with appropriate bolts to a suitable small platform that somehow resembles a non cleated pedal and add some sort of anti slippage material to it.
If you ever have attached your shoes to your pedals while not wearing them, you'll find not difficult to install and remove such contraption from your pedals.
However, I have never used this type of adaptor (I've been very tempted though) but I assume this is just for leisure pedalling, like a short trip to the corner store, I woluld not advise to use them for training, racing, stunts nor any type of demanding riding.
Since you mention loving your pedals, (wich I think means you really really like using your cleated shoes) I would advise to better carry your normal shoes and change them while you arrive to your destination. A small saddlebag, a stylized handlebar bag, or even a small backpack is a convenient solution to carry both your normal shoes while riding, and your cleated shoes while walking.