Preheat oven to 350°F (177°C). Grease a 9x13-inch baking pan.
In a medium bowl, whisk together flour, baking powder, baking soda, and salt; set aside.
In a large bowl, beat butter and sugar with an electric mixer until light and fluffy. Beat in eggs and vanilla until blended. Add mashed bananas and mix until combined.
Gradually add dry ingredients, mixing until just blended. Stir in coconut and macadamia nuts. Spread batter into prepared pan.
Bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean. Cool completely before cutting into bars.
Interesting Facts
Bananas are the most popular fruit in America, with Americans eating an average of 27 pounds each year.
Macadamia nuts are native to Australia and were first introduced to Hawaii in 1882.
Coconut is one of the most versatile ingredients, used in both sweet and savory dishes.