In A Large Pan Over Medium Heat, Lightly Saute The Artichokes And Garlic In Half The Butter, Do Not Brown. Add Potato And Stock, Bring To Boil. Then Lower Heat And Cover, Simmer Until Artichokes And Potato Is Tender About 10 Minutes. In Food Processor, Puree The Vegetables With Just Enough Of The Liquid To Achieve Smooth Consistancy. Return Puree To Pan. Stir Well, Season With Salt And Pepper. Reheat And Serve Immediately, Each Topped With A Bit Of The Remaining Butter.