Lightly spray a 7-inch springform pan with cooking spray.
To make the crust:
In a small bowl, combine graham cracker crumbs with melted butter. Mixture will resemble wet sand.
Pour the crust mixture into the prepared 7-inch springform pan and press using your fingers or a cup into the bottom and half way up the sides of the pan.
Pop into the freezer for 10 minutes.
To make the filling:
In a large mixing bowl, using an electric hand mixer set to medium-high speed, whip the cream cheese, sugar, flour and salt until smooth and creamy.
With the mixer set to low speed, add the eggs, one at a time, and mix just until combined. Do not over-whisk as this will incorporate too much air bubbles into the batter.
Using a spatula, mix in the heavy cream and vanilla
Pour the cheesecake batter into the prepared crust. Tap the pan gently on the kitchen counter a couple of times to remove any air bubbles.
Instant Pot instructions:
Cover the cheesecake with aluminum foil.
Pour 1 cup of water into the Instant Pot, place a trivet inside and put the cheesecake pan on top of the trivet.
Close the Instant Pot and set the valve to the sealed position. Pressure cook on “high” for 30 minutes.
When done, do a natural release for 20 minutes, then quickly release any remaining pressure.
Cool the cheesecake on a wire rack for 45 minutes. Gently mop up any moisture on the cheesecake surface with a paper towel.
Oven instructions:
Preheat oven to 330°F (165°C).
Wrap the bottom of the cheesecake pan with a double layer of foil.
Put the wrapped cheesecake pan in a big and deep enough baking pan and add boiling water to the baking pan. The water should go about halfway up the sides of the cheesecake pan.
Bake for 60-70 mins, or until the edge of cheesecake is set with the center slightly wobbly.
Turn off the oven and open the door slightly. Leave the cheesecake in the water bath in oven for 1 hour.
Remove the cheesecake from the oven and leave to cool on a wire rack to room temperature.
Use a knife to loosen the cheesecake from the edge of the pan. Remove the sides of the springform pan.
Cover the cheesecake with plastic wrap or foil and refrigerate for at least 6 hours, or overnight preferably.
To assemble:
In a microwave safe bowl, heat the heavy cream until it is steaming hot.
Break chocolate into small chunks and add to the heavy cream. Stir well.
Microwave again at intervals of 15-20 seconds, mixing after each interval, until chocolate is completely melted.
Let the chocolate cool, then pour over top of cooled cheesecake, getting some chocolate drips over the side of the cheesecake if desired. Reserve a little bit of the chocolate ganache for later.
Top the cheesecake with mini marshmallows. Using a blow torch, toast the marshmallows on top of the cheesecake. (See notes if you do not have a blow torch)
Drizzle leftover chocolate ganache on top of the cheesecake.
Pop into the fridge for 5-10 minutes so that the chocolate ganache sets. Slice and serve.
Notes
If you do not have a blow torch, place cheesecake under a broiler for a couple of minutes to toast the marshmallows.In colder climates, the leftover ganache may cool and become solid before being used again. If you need to, reheat it in the microwave before drizzling on top of the cheesecake.