Triple Layer Banana Cake /w Peanut Butter Fudge Icing

Cake:
In a large bowl, cream butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in bananas and vanilla. Combine the flour, baking powder, soda, and salt; add to creamed mixture alternately with buttermilk, beating after each addition. Pour into 3 greased and floured 9-inch round baking pans. Bake at 350^ for 25 to 30 minutes or until toothpick test is clean. Cool for 10 minutes in the pan, before removing from pan to wire racks to cool completely.
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Icing:
In a large bowl, beat the peanut butter, butter and corn syrup until smooth. Beat in powdered sugar and enough milk to be of spreading consistency. Frost between layers and over sides and top of cake. Garnish around top edge of cake and center with a single row of nuts.