Mississippi Sweet Potato Pie

Ingredients

• 1/2 tablespoon salt
• 3 eggs
• 1 1/4 cups sugar
• 1/2 teaspoon vanilla extract
• 1/2 teaspoon cinnamon
• 1/2 teaspoon nutmeg
• 1/2 teaspoon allspice
• whipped cream ((optional))
• 1 9-inch unbaked pie or tart shell
• 2 cups mashed sweet potatoes
• 3 tablespoons butter, (at room temperature)
• 1 1/4 cups scalded milk