Sour Cream Fudge

1. Prepare an 8x8 inch baking pan by lining it with aluminum foil and spraying it with nonstick cooking spray.

2. Combine sour cream, sugar, corn syrup, milk, and butter in a large saucepan over medium-high heat. Stir until sugar dissolves.

3. Boil the mixture, stirring occasionally, until it reaches 240 degrees (soft-ball stage). Remove from the heat and allow to cool to lukewarm without stirring, about 30-45 minutes.

4. Once the mixture is room temperature, add the vanilla and beat continuously until it becomes very thick and opaque. This can be done by hand or with an electric mixer fitted with a paddle attachment. Stir in the walnuts and pour into the prepared pan, spreading evenly.

5. Allow the mixture to set completely at room temperature before cutting it into 1-inch squares to serve.

Guide's Response to Sammyiul's comment:
It sounds as if you did not beat the fudge. After cooking and cooling, the fudge is a light caramel color and texture, but once it is properly beaten, it will become lighter in color and have the stiff texture of fudge. If you don't achieve the correct results when beating by hand, try using an electric mixer next time to make the job easier.
Elizabeth LaBau, About.com Guide to Candy