Preheat oven to 350 degrees.
Spray 2 donut pans with non-stick cooking spray. In a stand mixer add the banana and crushed pineapple and mix on medium until smooth.
Add eggs and oil and mix well again.
In a small bowl add the rest of the ingredients and whisk.
Add dry ingredients to wet and beat on low/ medium until batter is smooth.
Grab a piping bag and fill 3/4 full with batter. Cut a 1/2 inch opening in bag.
Squeeze batter and fill each donut cavity.
Place in oven and bake for 11-15 minutes.
Remove from oven and cool for a few minutes before transferring donuts to a cooling rack.
Allow donuts to cool before frosting.
If you have batter left over, wipe out a donut pan. Grease and repeat filling instructions.