Line small baking sheet with aluminum foil. Coat foil with the 1/2 teaspoon butter.
Heat together the 2 tablespoons butter, sugar and corn syrup in small saucepan, stirring, until melted, smooth and bubbly. Stir in walnuts. Increase heat to medium-high; cook 3 to 5 minutes, stirring constantly, until walnuts are fragrant and they stick together in a thick, syrupy mixture. Immediately pour walnut mixture onto prepared baking sheet, spreading quickly and as thinly as possible with metal spatula. Cool at least 10 minutes.
Peel nuts away from the foil. Divide walnut mixture in half. Coarsely chop half the mixture; break other half into small pieces.
In each of 8 parfait glasses or stemmed goblets, layer the following: pumpkin, ice cream, chopped nuts, pumpkin and ice cream. Sprinkle tops with the remaining small pieces of nuts. Serve. Makes 8 servings.