Start by baking the pumpkin. Cut it in half and scoop out the guts. Place cut side down on a foil lined cookie sheet. Bake at 350°F. for 2 hours. Let cool and scoop out pumpkin. Set aside.
For the crust
Place flour and salt in a food processor. Add cubes of butter. Put the lid on and turn it on. Pour water into the mixture while the food processor is running. Let it run until a ball of dough is formed. Lightly flour a clean area of your counter top. Place dough on floured surface and sprinkle a little more flour on top. Roll dough from center to edges, forming a circle about 12" in diameter. Wrap pastry around rolling pin. Unroll onto a 9-inch pie plate. Ease pastry into pie plate, being careful not to stretch pastry. Trim pastry even with rim of pie plate. Roll out extra pieces of dough and use a mini leaf cookie cutter to cut leaves and place around edge of crust. Save a little bit of dough to create the letters for the top of the pie.
Meanwhile, make the filling. Place all of the filling ingredients in a large bowl (reserving 1 tablespoon beaten egg) and beat with an electric mixer on medium until thoroughly combined. Pour into prepared crust. Brush the edges with beaten egg. Bake at 350°F. for 25 minutes. Remove from oven and add letters, plus some extra leaves. Brush with beaten egg. Bake for 25 minutes more. Let cool slightly before serving. Store at room temperature for one day, then store covered for up to 3 days.