Preheat the oven to 350º F.  Remove the cream cheese and eggs from the fridge for the cheesecake layer to come to room temperature. Line a 8x8 or 9x9 inch pan with aluminum foil or parchment paper. Spray lightly with non-stick cooking spray. 

In a mixing bowl, combine the properly measured flour, salt and cocoa powder. Stir together with a spoon until mixed. Set aside. 

In a small saucepan over low heat, combine the chopped unsweetened chocolate and cubed butter. Stir occasionally until it’s fully melted, about 5 minutes.

Meanwhile, in a larger mixing bowl, beat the sugar and eggs plus additional egg yolk with an electric mixer for 1 minute, until the mixture is pale yellow and doubled in volume. 

Once the chocolate is melted, pour it into the egg mixture. Then add the vegetable oil and vanilla extract. Stir with a spatula to combine. 

Spoon the flour mixture into the wet ingredients, mixing with a spatula just until combined. Do not continue to mix the batter once you can no longer see flour. 

Pour the brownie batter into the prepared pan and bake for 23-25 minutes, just until a crust forms on the top of the brownies. When looking for the crust to form, look for a color change in the brownies, the top will be a little lighter in color and might appear shiny. You can also carefully touch the brownies with a finger to determine if the crust formed. You shouldn’t have any brownie batter stick to your finger. 

Once a crust has formed, remove the brownies from the oven and allow them to cool for 5 minutes. Meanwhile, prepare the cheesecake layer. 

In a medium mixing bowl, beat 1 & 1/2 packages of cream cheese, sugar and vanilla extract until smooth, about 60-90 seconds.  Add in the egg and egg yolk, beating for about 30-60 seconds. 

Carefully pour the cheesecake batter over the brownies. I noticed that evenly pouring the batter over the brownies is key, instead of dumping it all in one place. Use a spatula to spread the cheesecake batter to the edges of the pan. Return the brownies to the oven and bake for 22-27 minutes. At this time check on the cheesecake to see how jiggly it is. If it’s still jiggly in the center, tent the pan with aluminum foil and bake for 4-5 additional minutes. The aluminum foil will prevent the cheesecake from browning.

Remove the pan from the oven and allow it to cool to room temperature. Then cover with plastic wrap and place in the fridge to chill for 2+ hours.

Cut into bars and serve. For clean cuts, fully wipe the knife clean between slices.