Plush Vanilla Dream Cake

Ingredients

• 3 teaspoons vegetable or canola oil
• 2 sticks unsalted butter
• 3 teaspoons vanilla extract
• 2 1/2 teaspoons baking powder
• 1/4 teaspoon salt
• 4 large eggs, at room temperature
• 2 cups all-purpose flour
• 1 pound soft icing sugar
• 1/2 cup unsalted butter
• 1 cup milk
• 2-4 tablespoons milk
• 1 1/2 cups caster sugar