Heat oven to 350°F. Lightly coat a 9 x 2-inch round baking pan with nonstick vegetable-oil cooking spray.
Mix together the flour, baking soda, cinnamon and salt in small bowl until well blended.
Beat together the butter and sugar in medium-size bowl until well blended. Beat in the sour cream, egg and vanilla until well blended.
On low speed and in 2 batches, beat the flour mixture alternately with the milk into the butter mixture, beginning and ending with the flour mixture; beat 1 minute. Pour batter into prepared pan.
Bake in 350°F oven for 30 to 35 minutes or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan on a wire rack for 15 minutes. Remove the cake from the pan. Let cake cool completely before frosting.
Melt the butterscotch morsels in the top of a double boiler, stirring, over simmering, not boiling, water. Remove the top of the double boiler from over the simmering water; let the butterscotch morsels cool slightly. Stir in sour cream until smooth. Let the mixture stand until set, about 5 minutes. Spread the frosting evenly over the top and sides of cooled cake. Garnish top of cake with the chopped pecans.