In a double boiler, over medium heat, whisk together the sweetened condensed milk, egg yolks and cornstarch. Continue to stir until the mixture starts to simmer and thickens.
Remove from heat and transfer to a small bowl and cover with plastic wrap to prevent a film forming on top of the pudding mixture.
Place the bowl in the refrigerator to chill.
To make the crust, place the nilla wafers, graham crackers, brown sugar and salt into a food processor and pulse until you get crumbs.
Add in the melted butter and pulse to combine.
Press the cookie mixture into the bottom of a 9” springform pan, pushing the sides up about halfway.
In a small bowl, heat the water and vanilla until simmering in the microwave.
Sprinkle the gelatin over the top and stir. Let it sit while combining the rest of the filling.
Place the pan into the refrigerator to chill for at least 30 minutes.
In a large bowl, mix 2 cups of heavy cream, cream cheese, mascarpone and salt.
Beat with an electric hand mixer until smooth.
Add in the chilled pudding and beat ‘until smooth and creamy.
Reheat the gelatin mixture for 10-15 seconds until it’s smooth when stirred.
Add the gelatin mixture to the cheesecake mix and beat until fully incorporated.
Spoon about half of the cheesecake into the springform pan and smooth in an even layer.
Slice the bananas and lay them in a flat layer over the entire surface of the cheesecake.
Top with the remaining cheesecake mix and smooth.
Place the cheesecake in the refrigerator to chill for at least 8 hours, preferably overnight.
To garnish, beat the remaining heavy cream (1 cup) and the powdered sugar together until stiff peaks form.
Place the whipped cream into a piping bag and create swirls around the edges of the cheesecake.
Decorate with extra nilla wafers.
Slice and serve!