Creating your Lemon Blueberry Sheet Cake is simple when you follow these clear steps:

1. Preheat Your Oven: Begin by preheating the oven to 350°F (175°C). Grease and flour a 9×13-inch baking dish to prevent sticking.

2. Mix Dry Ingredients: In a bowl, whisk together the flour, baking powder, and salt until well combined.

3. Cream Butter and Sugar: In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

4. Add Eggs: Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next.

5. Add Flavors: Mix in the lemon zest, lemon juice, and vanilla extract until combined.

6. Combine Mixtures: Gradually add the dry ingredients to the wet mixture, alternating with the milk. Mix until just combined; do not overmix.

7. Fold in Blueberries: Gently fold in the fresh blueberries, taking care not to break them up too much.

8. Pour Batter: Pour the batter into the prepared baking dish and spread it evenly with a spatula.

9. Bake: Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

10. Cool: Remove the cake from the oven and let it cool in the baking dish for about 15-20 minutes. Then transfer it to a wire rack to cool completely.

11. Add Glaze (Optional): If you’d like to add a lemon glaze, mix powdered sugar with lemon juice and drizzle over the cooled cake for extra sweetness.

Each of these steps aims to guide you through the simple yet rewarding process of making this incredible cake.