PRE-HEAT OVEN TO 325ยบ
MELT 6 TBSPS OF BUTTER. POUR INTO A GLASS MEASURING CUP. ALLOW TO SIT TILL THE WHITE SOLIDS FLOAT TO THE TOP. REMOVE AS MUCH AS YOU CAN WITH A SPOON.
PEEL THE POTATOES. USING EITHER A MANDOLIN OR A FOOD PROCESSOR, SLICE POTATOES INTO 1/8-INCH DISKS.
BUTTER AN OVEN-PROOF DISH WITH CLARIFIED BUTTER. ARRANGE A LAYER OF POTATOES IN A SPIRAL. SLATHER WITH CLARIFIED BUTTER. SALT AND PEPPER GENEROUSLY. ARRANGE THE SECOND LAYER ON TOP OF THE FIRST. SLATHER WITH BUTTER, SALT AND PEPPER, THEN ARRANGE A FEW SPRIGS OF THYME ON TOP.
PLACE IN THE OVEN AND BAKE FOR AROUND TWO HOURS, CHECKING THE POTATOES AFTER ABOUT 90 MINUTES TO SEE HOW THEY'RE DOING. WHEN THE POTATOES ARE CRISP AND BROWN ON THE EDGES, REMOVE FROM THE OVEN, DISCARD THYME SPRIGS AND SERVE.
SERVES 6