Peel a butternut squash using a vegetable peeler and/or a knife.
Remove the seeds and cut the squash into cubes.
Place the butternut cubes into a sauce pan and cover with water.
Bring the water to a boil and cook the squash until it is fork tender.
Drain the squash well. Use a fork, potato masher, or immersion blender to puree the butternut squash.
To make the pie filling
Add the measured butternut squash puree to a mixing bowl. Add the butter and stir until the butter has melted. If the puree is too cool to do this, melt the butter first.
Mix in brown sugar and eliminate any clumps that may form.
Add the evaporated milk, vanilla, and eggs. Whisk again.
Add the remaining ingredients and whisk until combined.
Pour filling into an unbaked 9" pie shell.
Bake for about 50 - 60 minutes in a 350 degree oven. The pie is done when a knife inserted in the center comes our clean or the center doesn't wiggle if you move the pie slightly.
Set the pie on a rack and let cool. Serve with whipped topping if desired.
Notes
You will need a 2 ½ to 3 pound whole Butternut Squash to make this recipe. Freeze any leftover butternut squash puree for future recipes. How to make pumpkin pie spice:
1 tablespoon Cinnamon
1 teaspoon Nutmeg
¾ teaspoon Allspice
1 teaspoon ground Ginger
Mix the spices together and store them in a spice jar or air-tight container.