Grease 12 muffins cups, or line 12 muffin cups with paper liners, and spray each liner lightly with non-stick spray. Preheat oven to 375.

For the praline topping, in a small bowl, mix together 1/3 cup brown sugar, sour cream and 1/4 teaspoon salt. Stir in pecans, tossing to coat. Set praline mixture aside.

In a large mixing bowl, whisk together the flour and next 5 ingredients. In a medium bowl, whisk the egg, buttermilk, pumpkin, 2/3 cup brown sugar and butter together, combining well. Add egg mixture all at once to flour mixture, and stir just until the dry ingredients are moistened.

Divide the batter evenly among the muffin cups, filling each well almost full. Use a spoon to sprinkle an equal amount of the praline topping on each muffin, pressing down slightly to embed the mixture into the top of each muffin.

Bake for 20 minutes, or until a wooden pick inserted in the muffin portion comes out clean. Cool in pan 5 minutes before removing to a wire rack to cool an additional 10 minutes. Best served warm.