Make the cake

1. Preheat oven to 350°F (176°C) and prepare a 9×13-inch cake pan with non-stick baking spray.
2. Combine the flour, baking powder, baking soda, cinnamon and salt in a medium-sized bowl and set aside.
3. Add the butter, oil, sugar and vanilla extract to a large mixer bowl and beat together until light in color and fluffy, about 2-3 minutes. Do not skimp on the creaming time.
4. Add the eggs one at a time, mixing until mostly combined after each. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
5. Add half of the dry ingredients to the batter and mix until mostly combined.
6. Add the buttermilk and mix until well combined.
7. Add the remaining dry ingredients and mix until well combined and smooth. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated. Do not over mix the batter.
8. Pour the batter into the prepared cake pan and bake for 22-28 minutes, or until a toothpick comes out clean.
9. Remove the cake from the oven and poke holes all over the top of the cake. I use a knife sharpener, but the end of the handle of a wooden spoon or spatula would work too.

Make the soaking mixture

1. While the cake is still hot, add the butter and brown sugar to a bowl and stir until combined. Microwave for about 1 ½ minutes, whisking very well half-way through to help the sugar melt. Microwave for another 30 seconds, whisking well afterward, until sugar is dissolved and mixture is smooth and well combined.
2. Add the sweetened condensed milk and cinnamon to the butter mixture and stir until combined.
3. Pour over the warm cake and use your spatula to spread it evenly around the cake, making sure than it doesn’t pool all in one area. Let cake cool completely.

Make the Frosting

1. Place the heavy whipping cream, powdered sugar, vanilla extract and cinnamon into a large mixer bowl. Whip on high speed until soft peaks form.
2. Add the cream cheese and continue whipping on low speed. It will begin to incorporate and smooth out, then stiff peaks should form. It should happen quickly.
3. Pipe or spread the whipped cream onto the cake and dust with additional cinnamon, if desired.
4. Refrigerate the cake until ready to serve.