Sift together cake flour, banana pudding mix, sea salt, and baking soda.
Preheat oven to 325F. Place the rack in the middle position. Liberally coat a 12-cup Bundt pan with nonstick baking spray.
In a stand mixer with paddle attachment, mix butter and sugar on high until pale yellow and fluffy, about 4 minutes.
Lower speed to medium and add eggs, one at a time, combining well after each egg, and scraping down the sides of the bowl as needed.
Turn the mixer to the lowest speed and slowly add sifted dry ingredients in two additions. Do not overmix.
Lastly, add sour cream, mashed banana, and both extracts and mix until just combined. Turn off mixer.
Pour cake batter into the prepared Bundt pan. Top with three-quarters of crushed Nilla wafers, reserving the rest for the top.
Bake for about 90-95 minutes, until golden brown and a toothpick inserted comes out with a few moist crumbs attached. Rotate cake halfway through baking.
Cool in pan on a wire rack for 20 minutes, then invert the cake onto a serving platter to continue cooling, for at least an hour before glazing and serving.