Combine flour and salt in medium bowl. Cut in shortening with pastry blender or two knifes until flour forms pea-sized chunks. Sprinkle one tablespoon at a time of the ice water over one small section of flour mixture and mix lightly with a fork. Repeat, rotating bowl, one section at a time.
Form 2/3 dough into large ball then press down to form a 5 to 6 inch diameter. Sprinkle flour on rolling surface and with flour-dusted rolling pin, roll dough into circle until dough is about 1/4" thick. Trim one inch larger than inverted 10" Pyrex pie plate. Carefully roll pastry onto rolling pin, then unroll it onto right-side-up pie plate. Press into pie plate. Fold edge under. Flute 1/2" high edge. Cover with plastic wrap. Refrigerate.
Cut the butternut squash into 1 inch cubes and cook in boiling water until tender, about 15 to 20 minutes. Drain. Combine butternut squash, evaporated milk, eggs, sugar, lemon extract, cinnamon, nutmeg, cloves, butter and brown sugar in mixing bowl and mix at medium speed for 5 minutes. Pour into chilled pastry shell. Cover edge of pie with long strip of aluminum foil to prevent over browning.
Bake 10 minutes at 400°F., reduce heat to 375°F and bake for 25 minutes. Remove foil. Bake for an additional 10 to 15 minutes, or until knife inserted in center comes out clean and crust is golden brown.