Banana Coconut Luau Cake

Name: Banana Coconut Luau Cake
Ingredients: 1/2 cup cake flour; 1/2 cup all-purpose flour; 2 teaspoons baking powder; 1 teaspoon ground ginger; 1 pinch salt; 1/4 cup butter, at room temperature; 1/4 cup sugar; 1/4 cup packed brown sugar; 1 large egg, at room temperature; 1/2 cup heavy cream; 1 ripe banana, mashed; 1/2 teaspoon vanilla extract; 1/4 cup macadamia nuts, toasted and roughly chopped; 2 tablespoons butter, at room temperature; 1 cup sugar; 1/4 cup water; 1 pinch cream of tartar; 1/4 cup coconut milk; Service:; 8 pineapple rings; 1 pint coconut ice cream; 1/2 bunch mint