Step 1: Preheat your oven to 350°F (175°C). Line a cupcake pan with paper liners.
Step 2: In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Set aside.
Step 3: In a large mixing bowl, cream together the unsalted butter and vegetable shortening until light and fluffy, about 3-4 minutes.
Step 4: Gradually add the granulated sugar to the butter mixture, beating well after each addition. Add the eggs one at a time, mixing until fully incorporated. Stir in the vanilla extract.
Step 5: Gently fold in the mashed bananas and buttermilk until well combined.
Step 6: Gradually add the dry ingredients to the wet mixture, mixing until just combined. Be careful not to overmix.
Step 7: Fill each cupcake liner about two-thirds full with the batter.
Step 8: Bake in the preheated oven for 18-20 minutes or until a toothpick inserted comes out clean. Let them cool for 5 minutes, then transfer to a wire rack.
Step 9: In a medium saucepan, heat the half-and-half over medium heat until it simmers. In a bowl, whisk together the egg yolks, sugar, cornstarch, salt, and vanilla until smooth. Slowly pour in the hot half-and-half, whisking constantly.
Step 10: Return the mixture to the saucepan and cook over medium heat, whisking constantly until thickened. Remove from heat and let cool to room temperature.
Step 11: Once the cupcakes are cool, top each with the vanilla pastry cream using a piping bag or spoon.
