Stir together pecans, brown sugar, and sour cream. Set aside.
Mash bananas in a medium bowl; add egg and next 3 ingredients, stirring just until dry ingredients are moistened.
Place paper baking cups in muffin pans, and coat cups with vegetable cooking spray.
Spoon batter into muffin cups, filling three-fourths full. Carefully spoon pecan mixture evenly in center of each muffin.
Bake at 400° for 18 to 20 minutes or until golden. Remove from pans immediately, and cool on wire racks.
Note: You can freeze muffins, if desired. To reheat, microwave at HIGH for 1 minute.