Heat 1 cup butter in large saucepan until melted.

Add pecans and mix well.

Bring to a boil. Cook until pecans begin to change color. (Mixture will foam over, so use a large saucepan.)

Add remaining butter and mix well. This will cool the pecan mixture and stop the cooking process.

Remove from heat.

Combine brown sugar, whipping cream and cinnamon in a saucepan and mix well. (Do not beat after you add whipping cream, just mix.)

Cook over low heat until blended, stirring constantly; increase heat--but be sure NOT to let it boil.

Cook to 230°F on a candy thermometer.

Stir in pecan mixture.

Add sour cream and vanilla and mix well.

Remove from heat.