In a large bowl, cream together the butter and brown sugar. Add sweet potatoes, eggs, milk, and corn syrup, beat until smooth. Add flour, cinnamon, nutmeg, and salt, beat until well combined. Pour into an un-baked pie shell.
Bake at 350 degrees for 55-60 minutes. Cool and serve with whipped cream.
Cook's Note: The original recipe called for 1 1/2 cups sugar, but I have reduced it to 1 cup. I didn't think it needed that much with the addition of corn syrup. I also added a bit of cinnamon (personal preference). It turned out beautifully!