Preheat 350ºF. Grease and lightly flour 2 9” cake pans.
In a medium bowl, sift together flour, sugar, baking powder and salt twice.
Pour cream and vanilla into a large bowl and beat with an electric mixer for 2 minutes or until just stiff. Add eggs, beat until blended. Add flour mixture; beat at low speed until batter is blended. Pour into prepared pans. Bake for 25-30 minutes or until center springs back when lightly touched. Cook cakes in pans on rack for 10 minutes. Remove cakes from pans and set on wire racks to finish cooling.
Frosting: In a medium bowl with an electric mixer beat butter with lemon rind until light and fluffy. Stir in sugar alternately with condensed milk, beating after each addition. Stir in lemon juice a bit at a time, until of desired tartness.
Place one cake top side down on platter, spread 1/3 of frosting on cake, set other layer top side up and frost top and sides with remaining frosting.