Preheat oven to 325 degrees.
Melt the butter and set it aside to cool.
Warm the milk until it is lukewarm and set it aside.
Whip the egg whites with the cream of tartar until stiff peaks form. Set aside.
Beat the egg yolks and the powdered sugar until light.
Beat in the melted (and cooled) butter, vanilla, cinnamon, ginger, cloves and allspice.
Mix in the flour.
Beat in the pumpkin and 1/2 cup of milk. Scrape down the sides of the bowl and then with the mixer on the lowest speed, add the remaining milk in a steady, slow stream.
Gently fold in/stir in the egg whites by hand.
Pour into a greased 9x9 inch pan.
Bake for 55-65 minutes. Cake will still be jiggly because it is custard but it shouldn't be runny.
Allow the cake to cool completely before cutting.