Preheat oven to 350°F (175°C). Grease and flour two 8-inch round cake pans.
Cream butter and sugar until light and fluffy. Add eggs one at a time, then vanilla and lemon zest. Alternate adding flour mixture and milk until smooth.
Divide batter between pans. Bake for 22–25 minutes, or until a toothpick comes out clean. Cool completely.
Whip cream to soft peaks. In a separate bowl, beat mascarpone, lemon curd, powdered sugar, and zest until smooth. Fold in whipped cream.
Place one cake layer on a plate, spread lemon cream filling, then top with the second layer. Dust with powdered sugar.
