Step 1

Preheat the oven to 350 degrees F (175 degrees C). Grease a fluted tube pan (such as Bundt®).

Step 2

Combine 1/4 cup sugar and cinnamon in a small bowl and mix in pecans. Sift flour, baking powder, baking soda, and salt together in another bowl.

Step 3

Beat 1 cup sugar and shortening together with an electric mixer in a large bowl until light and fluffy. Beat in banana, eggs, and vanilla extract. Add sour cream and mix until just blended. Add flour mixture and beat until blended.

Step 4

Sprinkle 2 tablespoons of sugar-nut mixture into the prepared cake pan. Top with 1/2 of the cake batter. Follow with remaining nut mixture and cake batter.

Step 5

Bake in the preheated oven until a toothpick inserted into the center of the cake comes out clean, 40 to 45 minutes. Cool for 5 minutes in the pan and then turn the cake out onto a wire rack to finish cooling.

Step 6

Melt butter in a saucepan over low heat. Add brown sugar and milk. Bring to a boil; continue to boil for 1 to 2 minutes. Remove from heat and add vanilla extract; mix in powdered sugar gradually. Top the cooled cake with the frosting.