Preheat oven to 325 degrees. Lightly spray an 8 by 4 inch loaf pan. (You can also use a 9 by 5 inch loaf pan - reduce the time to 50-60 minutes and watch it carefully) Line the pan with a piece of parchment paper creating a sling. The paper should cover the two long sides, the bottom and have a little overhang for easy lifting.
Sift together the cake flour, salt, baking powder and baking soda. Set aside. In a small bowl combine the ricotta cheese, lemon juice, lemon zest and vanilla. Set aside.
In a large mixing bowl, combine the butter and sugar with an electric mixer on medium-high speed until smooth and light, about 3 minutes. Scrape down the sides and bottom of the bowl and blend another 30 seconds.
Add the beaten eggs in three additions, mixing well after each addition until smooth. Scrape down the sides of the bowl as needed between each addition. With the mixer on low, add one-third of the flour mixture and blend just until incorporated. Add half the ricotta mixture, scraping down the sides of the bowl as needed. Repeat until you have used all the flour and ricotta mixtures. Using a rubber spatula, gently fold the batter pulling up from the bottom of the bowl to ensure it’s well blended.
If adding blueberries, gently fold into the batter taking care not to crush or burst the berries. Scoop the batter into the prepared pan and lightly smooth the top. Bake until golden brown on top and a toothpick inserted into the center comes out with a few moist crumbs attached, 60-70 minutes.
While the cake bakes, prepare the lemon syrup. Combine the lemon juice and granulated sugar in a small saucepan. Heat on medium-high and stir until the sugar is dissolved and it comes to a boil. Reduce the heat to medium and boil gently for 2 minutes. Remove from the heat and set aside to cool.
Remove the cake from the oven and cool for 20-30 minutes in the pan. Using the parchment paper to assist, remove the cake from the pan and transfer to a wire rack. Brush the top and sides of the cake with all the prepared lemon syrup. Continue to cool for about two hours before serving. Store in an airtight container at room temperature. This cake also freezes beautifully.