Start by preheating your oven to 350°F (175°C). Grease and flour three 9-inch round cake pans. This ensures your cakes slide out easily once baked. In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy. Expect this to take about 3-5 minutes.

Add the eggs one at a time, mixing well after each addition. Incorporate the vanilla extract and lemon zest for that delightful fresh note. In another bowl, whisk together the flour, baking soda, salt, and cinnamon. Gradually add these dry ingredients to the wet mixture, alternating with the buttermilk. Mix until just combined—do not overmix.

Divide the batter evenly among the three prepared pans. Bake in the preheated oven for 25-30 minutes or until a toothpick inserted in the center comes out clean. When done, allow them to cool in the pans for ten minutes before transferring them to wire racks to cool completely.

For the frosting, beat the softened cream cheese and butter together until smooth and creamy. Gradually add the powdered sugar, mixing on low speed until combined, then add the vanilla extract and a pinch of salt. Beat until fluffy.

Once the cakes are completely cool, it's time to assemble. Place one cake layer on a serving platter. Spread an even layer of frosting on top, then add another cake layer. Repeat the process. After adding the final layer, use the remaining frosting to coat the top and sides, creating a clean finish.

This is where your creativity shines! Arrange the blueberries in a square shape on the top left corner to represent the stars of the flag. Use the raspberries to create stripes across the remaining top area. Note that the raspberries should be arranged so that they resemble the flag's red stripes. Step back and admire your handiwork!