Beat butter with electric mixer until creamy. Gradually add sugar and beat well.
Combine water and milk in small bowl. Set aside.
Combine flour, baking powder and salt. Add to butter mixture alternately with milk mixture, beginning and ending with flour mixture. Mix at low speed until blended. Stir in rum.
Beat egg whites at high speed with clean beaters until stiff peaks form. Gently fold in batter. Pour batter into 3 greased and floured 9”round cake pans.
Bake 350 for 20-25 minutes or until wooden pick inserted comes out clean. Cool in pans for 10 minutes. Remove from pans and cool completely.
Notes
*****If using a metal bowl and heavy duty mixer to beat frosting, it will take 3-4 minutes to reach spreadable consistency. Frosting may take twice as long to thicken if using another type of mixer and glass bowl.
Recipe by Geaux Ask Alice! at https://geauxaskalice.com/tart-lemon-cheese-cake/