Combine shortening, butter, sugar, beaten egg, mashed banana and milk in a large bowl. Mix thoroughly.
In a separate bowl mix soda, baking powder, slat and chopped nuts.
Add dry ingredients to wet ingredients and mix just until combined.
Fold into a silicone loaf pan or a greased and floured metal loaf pan.
Bake for 1 hour in a 350 degree Fahrenheit oven.
Cool before serving.
Serve with Cranberry Iced Tea