Prepare the Cake

1. Preheat oven to 325F.
2. Prepare a 9 x 13 cake pan by greasing it with butter or spraying it with nonstick baking spray.
3. Combine cake flour, baking powder, baking soda and salt in a mixing bowl. Whisk to combine and set aside.
4. Add the butter and sugar to the bowl of a stand mixer with the paddle attachment and beat the butter and sugar on medium speed for 3 minutes until the sugar is well incorporated and the mixture lightens in color.
5. Add each egg, one at a time, to the butter with the mixer on medium speed, stopping to scrape down the sides of the bowl periodically to make sure everything is fully incorporated.
6. In a separate bowl, combine the milk, Greek yogurt, vegetable oil and vanilla and whisk together until fully combined.
7. Add half of the flour mixture you set aside earlier to the bowl of your stand mixer and mix in on the low setting. Then add in half of the Greek yogurt mixture to the mixer. Repeat to finish adding in the dry ingredients and the wet ingredients. Mix the batter for another 10 to 20 seconds so that the batter is nice and smooth.
8. Take the bowl off of the stand mixer and fold the jimmies into the batter.
9. Pour the batter into your prepared 9 x 13 pan and bake at 325 for 45 – 50 minutes. You’ll know it’s done when the top is a nice golden color and an instant read thermometer inserted into the center reads 200F – 205F.
10. Once the cake is done, remove the pan from the oven and put it on a cooling rack to cool for two hours. Do not add frosting to the cake before it’s fully cooled.
11. Once the cake has cooled, you can either keep it in the pan to decorate it, or invert it onto a platter.

Prepare the Frosting and Decorate

1. While the cake cools, make your frosting by combining the cream cheese, butter, and powdered sugar together in a bowl. You can use a stand mixer or hand mixer. Mix the cream cheese, butter and sugar for 1 minutes until they’re all mixed together and nice and smooth.
2. With the mixer on medium speed, slowly pour the heavy cream into the frosting until it’s all added. Then add in the vanilla and salt. Set the mixer on high and beat the frosting for 2 minutes until it gets light and fluffy. It should also be nice and stiff. If it seems too soft, add more powdered sugar by 1 Tbs at a time until you reach the desired consistency.
3. When you’re ready to decorate your flag cake, spread half of the frosting on top of the cake, then add the remainder into a piping bag fitted with a star tip. Decorate the top of the cake with raspberries, blueberries and more frosting to create stars and stripes.