Preheat the oven to 350 F. Line an 8x8” square baking pan with parchment paper on all sides (two overlapping sheets to make a + )

Melt the butter and mix with the cookie crumbs. Press into one layer into the bottom of the pan and bake for 10 minutes. Let cool, and lower the oven temperature to 325 F.

The cream cheese should have been out on the counter for at least a couple of hours, be very soft and at room temperature. Place it into a bowl along with the vanilla, salt and sugar. Beat with a hand mixer (you could also do this in a stand mixer, use the paddle attachment) until very smooth, and there’s no lumps. Add the sour cream and beat well.

Add the eggs and flour and beat to just combine.

Make the brownie batter

Melt the butter in the microwave until almost but not fully melted. Add the sugar and heat again, for about 30 seconds. Whisk vigorously for a full 30 seconds. Crack in the egg and whisk very well.

Add the cocoa, flour and chocolate hazelnut spread and whisk.

Onto the crust, pour half of the cheesecake batter. Dollop the brownie batter into the cheesecake, in 3-4 areas, using only half of the brownie batter. Use an offset spatula or butterknife to swirl the brownie batter in.

Pour the rest of the cheesecake batter over and gently smooth to create an even layer. Dollop the rest of the brownie batter in 3 big circles. Swirl again.

Place the pan in a 9x13” cake sheet pan. Fill just half the way with hot water.

Bake for 45 minutes. Turn off the heat and prop open the oven door to cool for about 15 minutes. Let cool on the counter for another 15 minutes then set in the fridge for at least six hours to chill. Serve cold.