Preheat your oven to 350°F. Grease a 9-inch round springform pan and line the bottom with parchment paper.
In a large bowl, whisk together the ricotta cheese and granulated sugar until smooth and well combined. Add the eggs one at a time, whisking thoroughly after each addition. Stir in the vanilla extract, lemon zest, and fresh lemon juice.
In a separate bowl, whisk together the blanched almond flour, cornstarch, baking powder, and salt.
Add the dry ingredients to the ricotta mixture and fold gently with a spatula until everything is just combined with no pockets of flour remaining. The batter will be loose and creamy.
Pour the batter into the prepared pan and smooth the top. Bake for 40-45 minutes, until the top is golden and the center is set but still has a very slight jiggle. A toothpick inserted near the center should come out clean or with just a few moist crumbs.
Let the cake cool in the pan on a wire rack for 20 minutes, then remove the springform ring and let it cool completely. Dust generously with powdered sugar and serve with fresh berries if desired.