Preheat the oven to 350°F / 175°C. Line the bottom of a 9" springform pan with parchment paper by placing the paper on the base, then snapping the pan together.

In a small microwave safe bowl, melt together the butter and chocolate chips in 30 second intervals, stirring in between each interval until the mixture is smooth.

Whisk in the cocoa powder and set aside.

In a medium sized mixing bowl, vigorously whisk together the eggs and sugar until the mixture is pale & fluffy.

Add the chocolate mixture into the egg mixture, and mix until combined.

Add in the flour and salt. use a rubber spatula to lightly fold the mixture together just until no flour streaks remain.

Pour ½ of the brownie batter into your lined springform pan. Smooth it out into an even layer, then bake for 15 minutes. In the meantime, start the cheesecake.

Add the cream cheese, sugar, and cornstarch to a large mixing bowl (or to a stand mixer fitted with the paddle attachment.)

Use a hand mixer (or stand mixer) to beat the ingredients together for 2 minutes, until no lumps remain.

Add the three eggs and vanilla into the cream cheese, and beat the mixture on low speed until the eggs have been fully incorporated.

Add in the heavy cream and again beat on low speed just until the mixture is cohesive.

Tap the bowl with the cheesecake filling on the counter a few times to get rid of any air bubbles.

Pour ½ of the cheesecake filling over the baked brownie. Use ½ of the remaining brownie batter to dollop over the cheesecake, then use a knife to gently swirl the brownie batter into the cheesecake.

Gently pour in the remaining cheesecake batter, smoothing it into an even layer. Dollop the remaining brownie batter over the cheesecake, and swirl it again.

Fill a 10×15" baking dish, or any larger pan that can reasonably fit the 9" springform inside of it, a third of the way with hot water. If desired, wrap tin foil around the bottom of your springform pan to avoid the possibility of water seeping into the springform.

Place the springform pan into the larger pan, then place the whole thing into the oven. Bake for 60-70 minutes, or until the cheesecake only slightly wobbles and reaches an internal temperature of at least 170°F / 76°C. If the cheesecake starts to brown on top, gently place a piece of tinfoil over the top of the pan.

Once the cheesecake is fully cooked, turn off the oven and leave the door slightly ajar with the cheesecake in it for 1 hr. before transferring it to the fridge to chill for at least 8 hours.

Place the chocolate into a small mixing bowl and set aside.

Bring the cream to a simmer - either on the stovetop, or by placing the cream in a large microwave safe measuring cup and heating it until it starts to bubble up.

Pour the cream over the chocolate, and mix until smooth.

Transfer the ganache to the freezer, and stir every 5-10 minutes until it has significantly thickened up.

Once the ganache has cooled and thickened, use a hand mixer to lightly whip up the mixture until it is fluffy and has lightened in color

Transfer the ganache to a piping bag fitted with your desired tip, and pipe it around the cheesecake. Serve and enjoy!