Step 1

Preheat oven to 350°. Crumble cookies into a food processor and pulse until very finely ground. (You should have a heaping 1½ cups.) Add butter and sugar; pulse until mixture is combined and sticks together when pressed between your fingers.

Step 2

Press mixture across bottom and up sides of a 9"-diameter pie dish with your hands. Freeze crust 5 minutes.

Step 3

Bake crust until slightly darkened around the edges, 8–10 minutes. Let cool.

Step 4

Place chocolate in a medium bowl. Heat cream in a small saucepan until just beginning to simmer; immediately pour over chocolate. Let sit, undisturbed, 5 minutes.

Step 5

Add butter to chocolate mixture and stir with a heatproof rubber spatula until smooth and glossy. Scrape ganache into crust and smooth out any bubbles. Chill, uncovered, until set, about 30 minutes.

Step 6

Stir granulated sugar and 2 Tbsp. water in a medium heavy saucepan to combine. Bring to a boil over medium heat, stirring to dissolve sugar, then cook, swirling occasionally but not stirring, until deep amber, 7–9 minutes. Remove from heat.

Step 7

Gradually add milk and cream to caramel, whisking constantly until smooth. The caramelized sugar may stick to the bottom of the pan at first but will eventually loosen and become smooth. Whisk in brown sugar, butter, and salt, then bring butterscotch to a boil.

Step 8

Whisk egg yolks and cornstarch in a large bowl until smooth. Gradually pour in butterscotch, whisking constantly until combined. Wipe out saucepan and scrape pudding mixture into pan. Cook over medium heat, stirring often, until pudding bubbles occasionally and starts to thicken, about 5 minutes. Strain pudding through a fine-mesh sieve into a large bowl and let cool 10 minutes.

Step 9

Scrape pudding into crust on top of ganache and smooth surface. Chill pie, uncovered, until pudding is set, at least 6 hours.

Step 10

To serve, scatter chopped chocolate around edges of pie filling, then pile bananas in the center.Do ahead: Pie (without chopped chocolate and bananas) can be made 3 days ahead. Cover and keep chilled.