My mother gave me a similar recipe 25 years ago and I have been making it for Thanksgiving every year since then.
Our filling recipe varies slightly in ingredients. Mine has 1 15 oz can pumpkin, 3/4 cup sugar, 1 tsp ground cinnamon, 1/2 tsp. salt, 1/2 tsp. ground ginger, 1/4 tsp. ground cloves, 2 eggs, 1 cup evaporated milk. This makes it more like true pumpkin pie in the middle.
Also, when putting the first layer in the pan, pat the bottom slightly higher on the sides to help keep the pumpkin filling in place.