Grease three 6-inch (15 cm) round cake pans and line the bottoms with cut-out parchment paper liners. Preheat the oven to 350°F (180°C)*.

In a bowl, combine the milk and vinegar. Let it sit for 5 minutes to curdle.

Meanwhile, place a sieve over a large bowl and sift together the dry ingredients. Stir to combine. Make a shallow well in the centre of the flour mixture.

Pour the milk mixture and remaining wet ingredients into the well of the dry ingredients. Mix until just combined, but be careful not to overmix**.

Divide the batter between the pans and tap them on the counter a few times to remove any air bubbles.

Bake the cakes in the oven on the center rack for 25 - 30 minutes, rotating the pans on the rack once at the halfway point. The cakes are done when a wooden skewer inserted into the centre comes out clean.

Allow the cakes to cool in the pan for 5 minutes before transferring them to a cooling rack. Carefully peel off the parchment liners and allow the cake to cool completely***.

While the cakes cool, prepare the buttercream frosting. In a large bowl, whip the butter with a electric hand mixer until fluffy, about 3 - 4 minutes.

Then add the powdered sugar and vanilla.

Beat the frosting for another 4 - 5 minutes, or until fluffy and lighter in colour.

Place the first layer of the completely cooled cake, rounded side up, on your serving dish****. Cover the cake with ⅓ cup of frosting. Use a spatula to smooth the frosting to the edge of the cake.

Place the second layer on the cake, flat side up and frost the same way as the bottom layer. Lastly, place the third layer on the cake, flat side up, to complete the cake.

Cover the top and sides of the cake in frosting.

Decorate the cake as desired. Slice, serve, and enjoy!