For the Cake:
Preheat oven to 350(F) degrees. Butter, flour and line 3 6-inch round cake pans.
In the bowl of a stand mixer fitted with the paddle attachment cream butter and sugar until fluffy, about 2 minutes.
Add in the eggs one at a time followed by the oil and vanilla extract.
In a separate mixing bowl sift together the flour, baking powder and salt.
Turn the mixer to low speed. Alternate adding the flour mixture and milk. Beat until batter is smooth, about 2 minutes.
Evenly divide batter amongst the prepared cake pans. Bake for 20 to 25 minutes, until the top bounces back to touch. Let cool completely before removing from pan.
For the Frosting:
In the bowl of a stand mixer fitted with the paddle attachment beat the butter and sugar until fluffy, about 5 minutes.
Add the vanilla, whipping cream and food colouring (if desired). Beat until whipping cream is fully incorporated, about 2 minutes. Set aside until ready to frost cake.
For the Topping:
To a saucepan add 300 mL whipping cream, whole milk and cornstarch. Whisk until cornstarch dissolves.
Turn heat to medium and add the condensed milk. Continuously whisk until mixture begins to thicken, about 5 minutes. Immediately remove from heat and add vanilla extract (as well as food colouring if desired).
Transfer to a mixing bowl. Cover with plastic wrap and gently press the plastic wrap against the top. Let cool to room temperature.
When ready to frost cake, whisk in the remaining whipping cream until fluffy and smooth. Run mixture through a fine mesh sieve if desired.
Begin with a layer of cake on a plate or round cake pad. Add 1/3 of frosting and smooth evenly to the edges. Using a tall piece of acetate, loosely wrap the cake and tape edges together.
Add second layer of cake and press down to flatten. This will ensure the buttercream reaches the edges. Add 1/3 of frosting and repeat.
On the final layer of frosting, ensure the frosting goes directly to the acetate edges so the ooze topping does not leak.
Pour ooze topping over the cake and finish with sprinkles.
When ready to serve, pull the acetate vertically off the cake & watch the topping ooze all over the cake. Slice and serve.