Fill a muffin pan with liners.
Preheat oven to 350 degrees.
Mix bananas and baking soda together and then set aside.
Cream together the shortening and sugar. Stir in eggs.
Then add flour,baking powder, buttermilk and salt. Mix well.
Ann bananas and baking soda mix. Add walnuts, if using.
Fill muffin liners ⅔ full
Sprinkle with streusel topping
Baking for 55-60 minutes. Rotating halfway.