Yield: 2 cakes 1 large egg 3 1/2 tablespoons vegetable oil 3 1/2 tablespoons buttermilk 1/4 cup granulated sugar 1/4 teaspoon pure vanilla extract 5 tablespoons self-rising flour Pinch of kosher salt 1/4 cup white chocolate chips 1/4 cup chopped macadamia nuts 1. In a large mug, whisk together the egg and oil with a fork. Stir in the buttermilk, sugar and vanilla. Add the flour and salt. Beat the batter until smooth. Divide the batter between two mugs. 2. Microwave separately for 30 seconds each. Top each mug with half of the chips and nuts then cook each mug, separately again, for 1 to 1 1/2 minutes more, until firm and risen.