Have all ingredients at room temperature. Preheat oven to 325. Generously grease and flour a 9X13 pan or two 9 inch round pans.
Sift flour with the baking powder, soda and salt. set aside.
Cream butter and sugar until fluffy. Add beaten eggs, banana's and vanilla. Beat well.
Add flour mixture to creamed mixture alternately with the buttermilk, starting and ending with flour mixture. Fold in nuts.
Pour into prepared cake pan. Bake for about 35 to 40 minutes, or until toothpick inserted into the center of the cake comes out almost clean.
While cake is baking, prepare the caramel glaze: In a large saucepan, combine sugar, butter, buttermilk, corn syrup and soda. Bring to a boil; then reduce heat to simmer for 5 minutes, stirring constantly. Glaze will be a caramel color. Remove from heat and stir in vanilla. NOTE: A large saucepan is needed because mixture will expand after coming to a boil. It will simmer down after about 3 minutes of cooking.
Once cake is done, remove cake from oven and poke holes in hot cake with a fork or meat fork. Slowly pour caramel glaze over hot cake spreading evenly over entire cake. Cool cake until glaze is totally absorbed, about 15 minutes. Turn out of pan, if desired. Cool cake completely.
Prepare cream cheese frosting: Cream butter and cream cheese until fluffy. Add vanilla and powdered sugar. NOTE: The amount of powdered sugar depends on how sweet you like the frosting. The cake is already sweet enough so I like a less sweet frosting that tastes more like cheesecake.
Chill the cake until frosting is set. Serve chilled. Refrigerate any leftover cake.