Heat oven to 375 degrees F, arrange rack in upper third, and place a baking sheet on rack while oven heats.
Meanwhile, roll dough on a lightly floured surface to a 12-inch diameter circle approximately 1/8-inch thick. Transfer dough to a 9 1/2-inch pie dish and trim edges so there is a 1/2-inch overhang. Use excess dough to press crust into pie plate. Fold edge of crust back on itself and press, as desired, into a decorative crust. (Can be made 2 days ahead and kept covered in refrigerator until ready to use.)
Pierce bottom of crust all over with a fork. Line pie with aluminum foil so it overhangs slightly and covers edges of pie crust and fill with uncooked rice, dried beans, or baking weights. Place pie dish on baking sheet and bake until crust is set and edges are slightly puffed up, about 25 minutes.
Gather foil together and remove along with weights. Continue to bake crust until it is thoroughly golden, about 15 minutes. Remove to a wire rack and let cool a few minutes before filling.
Meanwhile, peel 1 banana and place in a blender with milk, egg yolks, cornstarch, sugar, vanilla, and salt and process until smooth. Pour into a small saucepan, bring to a simmer over medium heat and cook, stirring constantly until mixture bubbles and is thick, about 7 to 8 minutes. Remove from heat and stir in butter, a few pieces at a time, until melted. Set aside to cool slightly.
Pour in filling into the pie shell and evenly smooth with a spatula. Slice remaining 3 bananas into 1/2-inch pieces and arrange on top of custard. Smooth whipped cream over top, loosely cover in plastic, and set in refrigerator until cool and set, at least 3 hours.
In a large bowl, mix together flour, salt, and sugar until well combined. Using clean hands, add butter and toss until just coated. Rub butter between thumb and forefingers to incorporate into flour mixture until butter is in lima bean-sized pieces and comes together in quarter-sized clumps when squeezed in palm, about 2 minutes. Add shortening, toss until just coated in flour, then rub into flour mixture until mixture forms pea-size pieces (some big chunks should remain) and comes together in fist-sized clumps when squeezed, about 1 minute. Drizzle in half ice water and rake through mixture with fingers until just moistened. Drizzle in remaining water 1 tablespoon at a time and comb through mixture with fingers to moisten. It will go from being a shaggy mess to coming together. Dough is moist enough when it is moistened through but is not wet when pressed. (Do not overwork the dough or it will become tough.)
While rotating the bowl with 1 hand, push dough between other palm and side of bowl to gather into a ball. Turn dough onto a piece of plastic wrap, press it into a flat disk, then close in wrap. Place in coldest part of refrigerator (usually back bottom shelf) at least 30 minutes before rolling out and forming into a crust.
Yield: about 1 pound dough (enough for 1 (9 to 10-inch pie dish))
Prep Time: 5 minutes Inactive Prep Time: 30 minutes Ease of preparation: intermediate Place very clean glass or metal bowl and metal whisk in freezer just until cold, about 5 minutes.
When everything is cold, place cream in bowl and begin to whisk until it froths up and starts to thicken, about 1 minute. Whisk vigorously until soft peaks form (the cream will hold a point when the whisk is lifted but will fall back into the bowl almost immediately), about 1 minute.
Add the liqueur and whisk until stiff peaks just form (the cream stays put on the whisk when it is lifted from the bowl), about 1 minute. Store covered in refrigerator until ready to use.
Yield: 1 1/2 cups Prep Time: 8 minutes Ease of preparation: easy