Prepare the Cake Layers:

Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a bowl, sift together flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, cream the butter and sugar until light and fluffy. Beat in the eggs one at a time, followed by the lemon zest, lemon juice, and vanilla extract.

Gradually add the dry ingredients, alternating with the buttermilk, starting and ending with the dry mixture. Mix until just combined.

Divide the batter evenly between the prepared pans and bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean.

Cool the cakes in the pans for 10 minutes before transferring to a wire rack to cool completely.

Make the Lemon Cream Filling:

In a mixing bowl, whip the heavy cream until soft peaks form.

In a separate bowl, beat the mascarpone cheese, powdered sugar, lemon juice, and lemon zest until smooth.

Gently fold the whipped cream into the mascarpone mixture until fully combined.

Assemble the Cake:

Place one cake layer on a serving plate. Spread a generous layer of lemon cream filling over the top using an offset spatula.

Place the second cake layer on top and spread another layer of the filling over the top. Reserve some filling for the sides if desired.

Decorate the Cake:

Dust the cake with powdered sugar and garnish with lemon slices or zest for an elegant finish.

Chill and Serve:

Refrigerate the cake for at least 1 hour before slicing to allow the flavors to meld. Serve chilled for the best texture and flavor.