Preheat the oven to 325°F. Spray a standard 9-inch or a deep-dish 9-inch glass pie dish with cooking spray.
In a large bowl, whisk together the evaporated milk, eggs, and vanilla extract until the eggs are well combined.
Add the pumpkin, sugar, pumpkin pie spice, and salt. Whisk until well combined.
Pour the pumpkin mixture into the prepared pie dish.
Bake at 325°F for 60 to 70 minutes or until a knife inserted in the center comes out clean. An alternate method is to give the pie dish a gentle shake. It is done when the filling is firm around the edges and the center has just a very slight jiggle (kind of like Jell-O).
Remove from the oven and place on a wire cooling rack. Cool completely, uncovered, at room temperature (this will take about 2 hours).
Cover with plastic wrap and chill in the refrigerator for at least 6 hours. I usually just let mine chill in the refrigerator overnight.
Slice and serve with whipped cream, if desired.