Follow these steps to create your Lemon Blueberry Layer Cake:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.
2. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, and salt.
3. Cream Butter and Sugar: In a large mixing bowl, cream the softened butter and granulated sugar until light and fluffy.
4. Add Eggs and Zest: Add the eggs one at a time, beating well after each addition. Mix in the lemon zest.
5. Add Milk and Lemon Juice: Gradually mix in the milk and lemon juice until well combined.
6. Combine Mixtures: Slowly add the dry ingredients to the wet mixture, mixing until just combined. Be careful not to overmix.
7. Fold in Blueberries: Gently fold in the fresh blueberries, ensuring even distribution throughout the batter.
8. Pour Batter: Divide the batter evenly among the prepared cake pans.
9. Bake: Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
10. Cool Cakes: Remove the cakes from the oven and let them cool in the pans for 10 minutes. Then, transfer them to wire racks to cool completely.
11. Prepare Frosting: In a mixing bowl, beat the softened butter until creamy. Gradually add powdered sugar, mixing until smooth. Incorporate blueberry puree, heavy cream, vanilla extract, and a pinch of salt.
12. Frost the Layers: Once the cakes are completely cool, place one layer on a serving platter. Spread a layer of blueberry frosting on top. Repeat with the second layer, then place the final layer on top.
13. Decorate: Frost the top and sides of the cake with the remaining blueberry frosting. Garnish with fresh blueberries and lemon slices, if desired.

These steps will guide you in crafting this incredible Lemon Blueberry Layer Cake, bringing summer flavors to your table.