Chicago-style cheesecake

Method :
For the crust:
1. Beat the butter and sugar together on medium speed until light and fluffy
2. Add vanilla extract and mix until combined.
3. Add the flour and the salt and beat on low speed until just combined.
4. Press the crust evenly into the bottom of the pan. Refrigerate until firm, about 30 minutes.
5. Pre-heat oven at 175 degree.
6. Prick the chilled crust several times with a fork and bake until golden, about 20 minutes.
7. Transfer to a wire rack and cool completely.

For the filling:
1. Pre-heat oven at 175 degree.
2. Beat the cream cheese on medium-low speed to break it up and soften it.
3. Add half the sugar and the lemon zest and beat on medium-low speed until combine.
4. Beat in the remaining sugar, flour, and salt until combined, another minute.
5. Mix well the vanilla extra with buttermilk and add in to the batter to beat until combine.
6. Add the egg yolk and beat for one minute.
7. Add the eggs, one at a time and beat to combine after each addition. (I am not sure is it cos I used buttermilk that caused the batter to be very running)
8. Grease the side of the cake pan. Set the pan on a rimmed baking sheet or aluminum foil to catch any spill.
9. Pour the filling onto the cooled crust and bake for 50 - 60 mins or until the cheesecake is firm around the edges and barely jiggles in the center. (the recipe didn't ask for water bath method but I used another tray half filled with hot water and position at the last row and bake the cheesecake in middle rack)
10. Transfer to wire rack and cool for 3 hours then wrap tightly with plastic and chill in the fridge for at least 3 hours and up to 4 days.
11. Unmould the cheesecake abd serve