Instructions

Make the Cake:

1. Preheat oven to 350°F (175°C). Line a 10×15-inch sheet pan with parchment paper and spray with nonstick spray.
2. In a bowl, whisk together cake flour and baking powder.
3. In a stand mixer, cream butter, sugar, and vanilla extract until light and fluffy (about 5 minutes).
4. Add egg whites one at a time, mixing well after each.
5. Alternate adding the flour mixture and milk in thirds, starting and ending with the flour. Mix until just combined.
6. Pour batter into the prepared pan and bake for 28-30 minutes, or until a toothpick inserted in the center comes out clean.
7. Let the cake cool completely, then refrigerate for 1-2 hours or freeze for 10-15 minutes to firm up.

Prepare the Blueberry Topping:

1. In a saucepan, combine 4 cups blueberries, sugar, lemon juice, and cornstarch.
2. Heat over medium until thickened and bubbly, then let cool.
3. Stir in the remaining ½ cup of fresh blueberries and refrigerate.

Make the Whipped Topping:

1. Chill a mixing bowl and whisk attachment for 15 minutes.
2. Beat cream cheese and sugar together on medium-high speed until smooth.
3. Add heavy cream and mix until soft peaks form. Increase speed and mix until stiff peaks form, then add vanilla and salt.

Assemble the Shortcake:

1. Slice the chilled cake in half horizontally.
2. Place one half on a serving plate and spread half of the blueberry topping over it.
3. Add ⅓ of the whipped topping over the blueberries.
4. Place the second cake layer on top, then spread the remaining whipped topping and blueberries over it.
5. Serve immediately or refrigerate until ready to serve.