Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
In a large bowl, beat together the mayonnaise, sugar, eggs, and vanilla extract until light and fluffy.
Add the dry ingredients to the wet ingredients in two batches, stirring until just combined.
Stir in the buttermilk.
Pour the batter into the prepared pan and bake for 25-30 minutes or until the cake is golden brown and a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 10 minutes before turning out onto a wire rack to cool completely.
Interesting Facts
This cake is not only moist and fluffy but also very easy to make.
Mayonnaise is a great substitute for butter in cakes.
Adding buttermilk to the batter gives the cake a light and airy texture.