In a large bowl, cream the shortening and sugar until light and fluffy.
Add the eggs, one at a time, beating well after each addition.
Beat in vanilla. Add bananas and mix well.
Combine the flour, baking powder, baking soda and salt; add to the creamed mixture alternately with sour cream, stirring just until combined. Stir in walnuts.
Pour into a greased and floured 10-in. fluted tube pan.
Bake at 350° for 50-55 minutes or until a toothpick inserted near the center comes out clean.
Cool for 10 minutes before removing from pan to a wire rack to cool completely.
Place a piece of waxed paper under the wire rack before adding the glaze.
Brown Butter Glaze
In a medium bowl, add powdered sugar.
Place butter in a small saucepan. Melt butter over medium heat until bubbly. Cook, stirring occasionally until golden brown. Remove from heat and pour butter into the bowl of powdered sugar.
Add milk and vanilla, stir until smooth.
Pour over the top of the cake and let it ooze over the sides. Use a metal spatula to help smooth it out.