Heat oven to 350°. Mix the lemon juice and milk and set aside. Grease and flour a loaf pan. In the bowl of a stand mixer, beat butter and sugar until light and fluffy. Beat in the egg, vanilla and lemon zest. In a separate bowl combine the flour, baking powder and salt. Add half to the butter mixture and mix until just incorporated. Add half the milk, then the second half of the flour mixture, ending with the milk, mixing just until incorporated after each addition.
Bake for 15-18 minutes or until a toothpick comes out clean. Cool for ten minutes, flip cake out of loaf pan onto a cooling rack and cool another 30 minutes.
Cut the top off of the cake so that it is a level rectangle and using the 3" cookie cutter, cut two 3" rounds from the cake. Spray a 4x11" square of parchment paper with cooking spray and wrap around the 3" round cake and tape closed to form a parchment wall.
Lemon Cheesecake Layer
In the bowl of a stand mixer and using the whisk attachment, whip cream into soft peaks. Add vanilla and 2 tbsp icing sugar then whip into firm peaks, scrape out into bowl and set aside. Whip cream cheese until completely smooth, add 3 tbsp icing sugar and whip until light and fluffy. Fold in two thirds of the whipped cream, then the lemon curd. Refrigerate the leftover one third whipped cream. Divide the cheesecake between the two cakes. Place cakes in the freezer for at least two hours to set.
Meringue
In the bowl of a stand mixer whip the egg, cream of tartar and vanilla into soft peaks. Slowly add the sugar while continuing to whip into hard peaks. Continue whipping until the meringue can stand up on it's own.
Assembly
Remove the parchment paper. Spread the whipped cream over the sides of the cakes and cover with graham crumbs by patting them on with your hands. Spoon half the meringue onto the top of each cake, use a spoon to create those pretty little peaks. With a torch, toast the meringue, then dive head first into these lovelies!