Preheat oven to 350F degrees. Grease a 9x13 inch pan with non stick spray.
Sift together the flour, salt, baking soda, and cocoa powder into a large bowl and whisk to combine.
In the bowl of a stand mixer add the oil, sugar, vanilla and eggs and beat together. Then beat in the milk.
Carefully beat the dry ingredients into the wet ingredients about 1 cup at a time.
Pour the batter into the prepared pan, and bake for 30 minutes, or until an inserted toothpick comes out clean. Let cool before you add the frosting.
For the Frosting
In the bowl of a stand mixer beat the butter until well softened.
Shift together the powdered sugar and the cocoa powder then whisk to combine.
Beat the cocoa powder & powdered sugar mixture into the butter about 1 cup at at time, alternating with 1 tablespoon of milk until the desired sweetness and consistency is reached.
Frost the chocolate cake and decorate with sprinkles. ENJOY!