How to Make It
Stir together flour, salt, and 3/4 cup of the sugar in a large saucepan. Whisk together milk and eggs in a bowl, and add to sugar mixture. Cook over medium-low, whisking constantly, until thickened 15 to 20 minutes. Remove from heat; stir in peanut butter, butter, and 1 1/2 teaspoons of the vanilla until mixture is smooth.
Fill a large bowl with ice. Place saucepan in ice, and let stand, stirring occasionally, until mixture is thoroughly chilled, about 30 minutes.
Meanwhile, cut bananas into 1/4-inch slices. Crumble 4 cookies; set aside.
Beat cream and remaining 1 teaspoon vanilla in bowl of a heavy-duty stand mixer with whisk attachment on high speed until foamy; gradually add remaining 6 tablespoons sugar, 1 tablespoon at a time, and beat at medium-high speed until stiff peaks form. (Do not overbeat.)
Line bottom of a 13- x 9-inch baking dish with cookies slightly overlapping. Top with half of the bananas and half of the pudding mixture. Repeat layers once. Top with sweetened whipped cream. Cover and chill 2 to 24 hours. Top with reserved crumbled cookies and peanuts. Sift unsweetened cocoa over the top.