Preheat your oven to 350°F and lightly grease a 9x13 inch baking pan with butter. Whisk together 2 cups flour, 2 tsp baking powder, and 1/2 tsp salt in a bowl. Set this dry mixture aside so you're ready to go when the wet ingredients are done mixing.

Cream 1/2 cup softened butter with 1 1/2 cups sugar using an electric mixer for about 3 minutes until it's light and fluffy. You'll know it's ready when it looks pale and almost cloud-like. This step is crucial — don't skip it because it adds air to your cake.

Add 4 large eggs one at a time to the butter mixture, beating well after each egg goes in. Pour in 1 tsp vanilla powder and mix until combined. The mixture should look smooth and creamy at this point, though it might seem a little thick.

Alternate adding the dry ingredients and 1 cup milk to the wet mixture, starting and ending with dry ingredients. Mix on low speed, adding about one-third of the flour mix, then half the milk, then another third of flour, then the rest of milk, then final flour portion. Don't overmix or your cake gets dense (I learned this the hard way).

Pour the batter into your prepared pan and smooth the top with a spatula. Bake for 35 minutes until a toothpick inserted in the center comes out clean or with just a few crumbs. The kitchen will smell absolutely incredible around minute 30.

Let the cake cool completely in the pan for at least 30 minutes before decorating. Spread the 1 cup strawberry jam across the top as your base layer, leaving about an inch border on all sides. This jam layer is your glue for the fruit.

Arrange 1 cup blueberries in the upper left corner in a rectangle shape to create your "canton" section, then arrange 1 cup sliced strawberries in stripes across the rest of the cake. Whisk together 1/2 cup powdered sugar, 1 tbsp milk, and 1 tsp lemon zest, then drizzle over everything for a finishing touch.