Preheat oven to 350°F Line muffin pan with paper liners.
In a medium bowl, combine flour, baking powder and salt.
In a bowl, using electric mixer, beat butter and sugar until light and fluffy. Beat in vanilla.
Add eggs, one at a time, beating well after each addition. Add sour cream and beat until smooth.
Add flour mixture and beat just until combined.
Topping: In a medium bowl, combine sugar, walnuts, chocolate chips and cinnamon. Spoon batter into prepared muffin cups, filling halfway. Sprinkle evenly with half of the topping. Spoon in remianing batter and sprinkle with remaining topping.
Bake in preheated oven for 24 minutes or until puffed, golden and a tester inserted into center comes out clean.
Let cool in pan on rack for 5 minutes. Remove from pan and let cool completely on rack.