In a large bowl, beat the pumpkin, evaporated milk, eggs, sugar and pumpkin pie spice together until smooth.
Pour half of the batter into one unbaked pie shell, and the other half of the batter into the other pie shell.
Sprinkle the dry cake mix over the pies, splitting it equally.
Drizzle the melted butter over each of the pies, also dividing the butter equally. Top the pies with the chopped walnuts.
Bake the pies at 350 degrees for 45-55 minutes, or until a knife inserted in the center comes out clean.
Allow the pies to cool on a wire rack.
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Notes
If you don't want the pie crust, pour the pumpkin mixture into a greased 9x13 pan. Then sprinkle the cake mix, butter and walnuts on top of that. Bake this dessert at 350 degrees for 1 hour.