Preheat the oven to 175°C (350°F) and set the oven rack in the middle position.
Set aside a large deep baking pan or roasting pot, the pan is used as a water bath during baking.
Shift together the flour, salt, cocoa, cinnamon, baking powder, and baking soda and set aside.
In a mixing bowl with a paddle attachment, add the butter and sugar and cream the mixture until smooth. light and fluffy.
If you don’t have a mixing machine, add the butter and sugar into a medium-size bowl and beat until light fluffy and smooth.
Mix in the egg and continue to mix or beat for a few seconds.
Add in 1/3 of the flour mixture along with 1/2 of the milk into the butter mixture and mix or beat on medium speed for 10-20 seconds.
Repeat by adding half of the remaining flour and the rest of the milk and continue to beat or mix for about 20 seconds.
Add the remaining flour mixture and beat and mix until batter is well combined and smooth. This will take about 3-5 minutes.
Pour the chocolate cake batter into the bundt pan and spread it evenly throughout, and set aside.