1 tablespoon Kahlúa, or other coffee-flavored liqueur
1 teaspoon vanilla extract
2 large or 3 small ripe, firm bananas
3 large egg whites
1/4 teaspoon cream of tartar
1/2 cup granulated sugar
1 teaspoon vanilla extract
To make crust: Coat a 9-inch pie plate with cooking spray. Melt it in a small saucepan over low heat, then cook it for about 30 seconds, swirling the pan, until the butter turns light brown. Immediately remove the pan from the heat and add oil. Set aside.
Stir together flour, 1 tablespoon granulated sugar and salt in a medium bowl. Slowly stir the butter mixture into the flour mixture until the mixture is crumbly. Gradually stir in enough ice water so that the dough will hold together in a ball. Press the dough into a flattened disk.
Place two overlapping lengths of plastic wrap on the work surface. Set the dough in the center and cover with two more sheets of plastic wrap. Roll out into a circle about 12 inches in diameter. Remove the plastic wrap from the top and invert the dough into the prepared pie plate. Gently press the dough into the bottom of the pie plate. Remove the remaining wrap. Fold the edges under and crimp. Prick the bottom with a fork. Cover and place in the freezer for 10 minutes. Meanwhile, preheat oven to 400 °F.
Line the pastry shell with a piece of foil or parchment paper and fill with pie weights or dried beans. Bake for 10 minutes. Remove weights or beans; protect the edges with strips of foil. Bake until the crust is golden, 10 to 12 minutes longer. Cool on a wire rack. Reduce oven temperature to 350 °F.
To make filling: Whisk together 1/4 cup evaporated milk, egg, brown sugar, cocoa and cornstarch in a mixing bowl. Heat the remaining 1 cup evaporated milk in a heavy saucepan over medium heat until steaming; whisk into the egg mixture. Return the mixture to the pan and cook over medium heat, whisking constantly, until it bubbles and thickens, about 2 minutes. Remove from the heat and add chocolate, stirring until melted. Stir in Kahla (or other liqueur) and vanilla.
Peel and thinly slice bananas, arranging in the bottom of the baked pie shell. Spoon in the chocolate filling, spreading evenly. Set aside while you make the meringue.
To make meringue: Preheat oven to 350 °F. Beat egg whites in a large bowl with an electric mixer until frothy. Add cream of tartar and beat until soft peaks form. Slowly add 1/2 cup granulated sugar, beating until stiff, shiny peaks form; blend in vanilla. Spread the meringue over the filling, sealing to the edge of the crust. Make attractive peaks. Bake until the top is browned, about 15 minutes. Cool the pie on a wire rack for about 2 hours before serving.