Preheat the oven to 350°F (175°C) and line an 8x8-inch baking pan with parchment paper.

Whisk the all-purpose flour, baking powder, baking soda, and salt together in a medium mixing bowl.

Whisk the eggs and granulated sugar in a large mixing bowl for 1 minute until light and frothy.

Add the light olive oil, sour cream, zest from the lemons, fresh lemon juice, and 1 teaspoon vanilla extract to the egg mixture.

Whisk the wet mixture until smooth and fully combined.

Sift the flour mixture into the wet mixture using a fine-mesh sieve.

Gently fold the batter with a rubber spatula until just combined; do not overmix.

Pour the batter into the prepared baking pan and smooth the surface.

Bake the cake for 27 to 28 minutes, until a toothpick inserted in the center comes out clean.

Cool the cake completely in the pan before cutting and decorating.

Combine the cold mascarpone, powdered sugar, remaining 1 teaspoon vanilla extract, a pinch of salt, and lemon zest in a mixing bowl.

Mix the mascarpone mixture until smooth and thick.

Chill the mascarpone cream for 15 minutes if it is too soft to pipe.

Press a wide paper dessert cup firmly into the cooled cake to cut out four cake rounds.

Slice each cake round horizontally with a serrated knife if you want layered dot cakes.

Pipe or spread lemon mascarpone cream between the cake layers and over the tops.

Roll the cream-topped cakes in crushed pistachios, if using, to coat the tops.