Preheat the oven to 350°F (175°C). Grease a 9-inch baking pan.
Cream butter and sugar together until fluffy.
Add eggs one at a time, beating well. Stir in vanilla.
In another bowl, combine flour, baking powder, baking soda, and salt.
Gradually add the flour mixture to the wet ingredients, alternating with sour cream.
In a small bowl, mix brown sugar and cinnamon.
Pour half the batter into the pan, sprinkle with half the cinnamon mix.
Add remaining batter, then top with the rest of the cinnamon and pecans.
Bake for 40 minutes or until a toothpick comes out clean.
Cool slightly before serving.