Begin by preheating your oven to 350°F. Grease and flour two 9-inch round cake pans.

In a large mixing bowl, combine the granulated sugar and vegetable oil. Use an electric mixer or whisk to mix them together until well blended.

Add the eggs, one at a time, mixing well after each addition.

Stir in the lemon zest, lemon juice, and lemon extract.

Incorporate the light sour cream into the mixture and stir until smooth.

In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk.

In a small bowl, toss the blueberries with the 2 tablespoons of flour. Gently fold the blueberries into the batter.

Divide the batter evenly between the prepared pans and smooth the tops.

Bake in the preheated oven for 25-30 minutes, or until the cake layers are golden and a toothpick inserted comes out clean.

Allow the cakes to cool in the pans for about 10 minutes before turning them out onto a cooling rack.

In another bowl, whip the heavy cream, powdered sugar, and vanilla extract together until soft peaks form.

Beat the cold mascarpone cheese until smooth, then gently fold in the whipped cream until fully combined.

Place one layer of cake onto a serving platter and spread lemon curd over the top.

Use some mascarpone frosting to cover the lemon curd layer.

Add the second layer of cake and frost the entire cake with the remaining mascarpone mixture.

Decorate the top of the cake with extra blueberries and a drizzle of lemon curd if desired.

Allow the assembled cake to set in the refrigerator for about 20-30 minutes before serving.