Sour Cream Lemon Pie Filling

I wish I didn't know how to make this. It would be better for my fitness goals.

Sour Cream Lemon Pie

2 cups sugar
7 T cornstarch (I put in a 1/2 cup because I am lazy.)
1 cup lemon juice
6 egg yolks, lightly beaten
2 cups milk
1/4 cup butter
1 cup sour cream
1 baked and cooled 9 inch pie shell
whipped cream or cool whip

Combine sugar, cornstarch, juice, egg yolks, and milk in large saucepan. Cook over medium heat until thick and bubbling, whisking constantly to avoid scorching. Stir in butter, stirring until completely melted. Cool mixture to room temperature. Pour half of the mixture into the pie shell. Stir sour cream into remaining lemon mixture and pour on top of filling in pie shell. Cover and refrigerate overnight, then top with whipped cream or Cool Whip.