Preheat the oven to 350 degrees Fahrenheit and spray a 13” x 9” baking pan or casserole dish with cooking spray.

Add the flour, sugar, salt, baking powder, and baking soda to a large bowl and mix to combine the dry ingredients.

In a separate bowl, Whisk the avocado, milk, eggs, and vanilla extract together to combine the wet ingredients.

Pour the dry ingredients into the bowl with the wet ingredients and mix well until a smooth batter forms.

Pour the cake batter into the prepared baking dish and spread it into an even layer. Bake on the center rack of the preheated oven for 30-40 minutes (mine takes 30), or until the cake tests clean. Insert a digital thermometer into the center of the cake. If it is 190 degrees or higher (ideally 190 to 205 max), it is ready.

Remove the cake from the oven and place it on a wire rack to cool. Let the cake cool to room temperature before frosting it.

Pour the heavy whipping cream into the bowl of a stand mixer fitted with the whisk attachment. Whisk on low speed for 1 minute, until the cream is bubbly, then increase the speed to medium ot high speed and continue whisking for another 2 to 4 minutes, or until soft to stiff peaks form.

Spread the whipped cream over the cooled cake in an even layer.

Press 4 to 5 rows of blueberries in the upper left corner of the top of the cake to make the star portion of the American flag.

Thinly slice fresh strawberries and lay them into vertical layers with plenty of overlapping to create the stripes of the flag.

Slice the cake using a sharp knife and a spatula to lift the slices out of the cake pan. Note that the slices will be slightly messy given the soft nature of whipped cream. You can always sprinkle more fresh blueberries or slices strawberries on top of each slice or use a butter knife to clean up the whipped cream.