Instructions

1. Preheat the oven to 350ºF. Grease and flour a 9×13-inch baking dish.
2. In a large bowl (or the bowl of a stand mixer fitted with the paddle attachment), beat the sugar and butter together until it is lighter in color and smooth. Beat in the eggs, one at a time, scraping down the sides of the bowl as needed. Beat in the vanilla extract.
3. Add the flour, baking powder and salt, and mix just until mostly combined. With the mixer on low, add the milk and continue to beat just until the mixture is smooth, making sure to scrape the bottom and sides of the bowl.
4. Pour the batter into the prepared baking dish and bake until a tester inserted in the center comes out clean, 30-40 minutes.
5. Let the cake cool completely.
6. Once cool, make the frosting. In another large bowl, beat the butter until light and smooth. Beat in the vanilla and salt. Start adding in the powdered sugar, 1/2 cup at a time, mixing completely after each addition. Add enough cream and/or more powdered sugar until you have reached your desired thickness. Continue to beat the frosting for another 5-7 minutes, until light and fluffy.
7. Spread 1/2 of the frosting over the top of the cooled cake. Decorate in a flag pattern with the blueberries and strawberries.
8. Use the remaining frosting to decoratively pipe in the white stripes, if desired.
9. Slice and serve.