1. Preheat oven to 350°.
2. Coat 18 mini Bundt cups with baking spray.
3. Weigh or lightly spoon flour into dry measuring cups, and level with a knife. Combine flour, baking powder, baking soda, 1/2 teaspoon salt, and cinnamon in a bowl, stirring well with a whisk.
4. Place granulated sugar and 12 tablespoons butter in a large bowl; beat with a mixer at medium speed until well blended. Add eggs, 1 at a time, beating well after each addition. Beat in 1 teaspoon vanilla. Add flour mixture and buttermilk alternately to butter mixture, beginning and ending with flour mixture. Fold banana, pecans, and pineapple into batter.
5. Spoon batter evenly into prepared pans. Bake at 350° for 18 minutes or until a wooden pick inserted in centers comes out with moist crumbs clinging. Cool 5 minutes in pans on a wire rack; remove from pans.
6. Combine powdered sugar, bourbon, melted butter, and 1/4 teaspoon vanilla; stir until smooth. Drizzle over cakes.
Doubling Up: You'll only need a touch of the bourbon glaze, but for sugar hounds, you can double the glaze and garnish with more.