Banana Cupcakes with Vanilla Pastry Cream Frosting
Banana Cupcakes:
2¾ cups all-purpose flour
1¼ teaspoons baking powder
1 teaspoon baking soda
½ teaspoon salt
½ cup (4 ounces) unsalted butter, at room temperature
¼ cup vegetable shortening, at room temperature
1¾ cups granulated sugar
2 teaspoons vanilla extract
2 eggs
1½ cups mashed very ripe bananas (about 4 bananas)
½ cup buttermilk
For the Vanilla Pastry Cream:
3 cups half-and-half
6 large egg yolks
½ cup granulated sugar
3 tablespoons cornstarch
¼ teaspoon salt
1 teaspoon vanilla extract
To Make the Banana Cupcakes:
1. Preheat the oven to 325 degrees F. Line two 12-cup cupcake pans with paper liners.
2. Whisk together flour, baking powder, baking soda, and salt together into a large bowl and set aside.
3. Cream butter and shortening. Add sugar and vanilla and beat until fluffy.  Scrape down the bowl, add the eggs, and beat until just combined. Scrape down the bowl again and add the bananas. Beat until just combined. Slowly add the flour mixture, alternating with the buttermilk, in three additions, beginning and ending with the flour mixture. 
4. Fill the cupcake liners about three-quarters full. Bake for 20 to 25 minutes, rotating the pans halfway through the baking time
Vanilla Pastry Cream:
1. Set a fine-mesh sieve over a medium bowl.
2. In a medium saucepan, bring the half-and-half to a simmer and keep warm.
3. In a medium bowl, whisk together egg yolks, sugar, cornstarch, and salt until the mixture is pale, about 1 minute. Whisk half of the warm half-and-half into the egg yolk mixture, then pour that mixture into the remaining half-and-half in the saucepan and cook over medium heat, whisking constantly, until thickened. Remove from the heat and whisk in the vanilla. Strain the pastry cream through the sieve and press a piece of plastic wrap directly onto the surface of the cream to prevent a skin from forming. Put in the refrigerator for about 1 hour, or until chilled.