In this corner there’s Mickey D’s, the fast food kingpin that’s ruined many a Lenten fast by dangling its signature, limited-time-only “Shamrock Shake” in front of sweets-seekers for more than four decades.

And in the other corner we have Restaurant Associates, the scrappy congressional caterer looking to keep frozen confection lovers on Capitol Hill by offering their version of the seasonally inspired treat.

Were this an actual boxing match, RA would get KO’d in the first round.

Not only does McDonald’s score major points in terms of presentation (the complimentary whipped cream and maraschino cherry are nice touches) and value (three sizes, all less than $3; the Senate American Grill charges $2.55 for a small and $3.05 for a large), but its version tastes so much better than the lazily attempted knockoff.

The original is thick and rich, providing a steady draw through the straw. RA’s copy is straight up watery. And while the recipe list is surprisingly short — vanilla ice cream, milk, green food coloring and mint flavoring will get you there — the Senate version is barely tinted green (uneven coverage), and smacks more of malt than breath-freshening herbs.

Taste test ’em yourself through Saturday.

Otherwise, you’ll have to wait until 2014 to slurp green goop by the gallon.