In a large mixing bowl, combine your cake mix, egg whites, vegetable oil, almond extract, and milk. Beat on medium speed for about 2-3 minutes until smooth.

Preheat your oven to 350°F (175°C), grease and flour your cake pan, then pour the batter into the pan. Bake for 30-35 minutes until a toothpick comes out clean.

Once baked, let the cake cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.

In a saucepan, combine flour and milk over medium heat until thickened, about 5-7 minutes, then let cool.

Beat softened butter and powdered sugar until light and fluffy, then gradually add the cooled flour mixture and almond extract until airy.

Frost the cooled cake with the buttercream, smoothing it out for an even finish.