Preheat the oven to 350°F and line a baking sheet with parchment paper. Set aside.

In a stand mixer fitted with the paddle attachment, beat together the butter, granulated sugar, and brown sugar on medium-high speed until light and fluffy, about 2 minutes.

Use a silicone spatula to scrape down the sides and bottom of the bowl, then add the egg, and vanilla. Beat on medium-high until smooth and fluffy, about 1 minute.

Add the flour, baking powder, baking soda, and salt and beat on low speed until just combined and no streaks of flour remain, about 30 seconds, scraping down the bowl as needed. Last, add the nilla wafer crumbs and mix until combined.

Use a 1 ½ ounce cookie scoop to portion out equal amounts of dough. Roll the dough in your hands to smooth the edges, then place on the prepared baking sheets, spacing the dough balls about 2 inches apart.

Bake the cookies for 12 minutes or until they’ve puffed up and are set and firm around the edges, but still soft in the middle. Set aside to cool until set, about 5 minutes, before transferring to a cooling rack to cool completely.

While the cookies are baking make the vanilla pudding for the topping. Sprinkle the vanilla pudding mix into a medium sized bowl and whisk in the milk and salt. Continue to whisk until the pudding has thickened and is smooth. Cover and place in the fridge.

Once the cookies are completely cool, in the bowl of a stand mixer fitted with the whisk attachment, beat the heavy cream until medium peaks forms. Add the vanilla pudding to whipped cream and fold to combine.

Transfer to a piping bag (or plastic bag!) with the tip snipped off.

Top each of the cooled cookie with a few banana slices and then pipe a layer of the vanilla cream mixture on the top. Use the back of a spoon or an offset spatula to spread into a smooth layer.

If desired top with another banana slice and some Nilla wafer crumbs! Enjoy!