3/4 lb. butter (3 quarter-lb. sticks), cut into 1/4 inch bits
1/2 c. vegetable oil
40 sheets filo pastry, each about 16 inches long & 12 inches wide, thoroughly defrosted if frozen
4 c. shelled walnuts pulverized in a blender or with a nut grinder or mortar & pestle

Clarify the butter in a heavy saucepan or skillet in the following fashion: Melt the butter slowly over low heat without letting it brown, skimming off the foam as it rises to the surface. Remove the pan from the heat, let it rest for 2 or 3 minutes, then spoon off the clear butter and discard the milky solids at the bottom of the pan.

Preheat the oven to 350 degrees and stir the vegetable oil into the clarified butter. Using a pastry brush coat the bottom and sides of a 13 x 9 x 2 1/2 inch baking dish with bout 1 tablespoon of the mixture.

Fold a sheet of filo in half crosswise, lift it up gently and unfold it into the prepared dish. Press the pastry flat, fold down the excess around the sides an flatten it against the bottom. Brush the entire surface of the pastry lightly with the butter and oil mixture, and lay another sheet of filo on top, folding it down and buttering it in similar fashion. Sprinkle the pastry evenly with about 3 tablespoons of walnuts.

Repeat the same procedure using two sheets of buttered filo and 3 tablespoons of the pulverized walnuts each time to make 19 layers in all. Spread the 2 remaining sheets of filo on top and brush the baklava with all of the remaining butter and oil mixture.

With a small, sharp knife score the top of the pastry with parallel diagonal lines about 1/2 inch deep and 2 inches apart, then cross them diagonally to form diamond shapes. Bake in the middle of the oven for 30 minutes. Reduce the heat to 300 degrees and bake for 45 minutes longer or until the top is crisp and golden brown.

SYRUP:

1 1/2 c. sugar
3/4 c. water
1 tbsp. fresh lemon juice
1 tbsp. honey

Meanwhile, make the syrup. Combine the sugar, water and lemon juice in a small saucepan and, stirring constantly, cook over moderate heat until the sugar dissolves. Increase the heat to high and, timing it from the moment the syrup boils, cook briskly, uncovered, for about 5 minutes, or until the syrup reaches a temperature of 220 degrees on a candy thermometer. Remove the pan from the heat and stir in the honey. Pour the syrup into a bowl or pitcher and set it aside.

When the baklava is done, remove it from the oven and pour the syrup over it. Cool to room temperature and just before serving, cut the baklava into diamond- shaped serving pieces.