Cream the butter and sugar on medium speed using a mixer or hand beaters, until fluffy. Add the egg yolks, one at a time. Add the lemon juice, flour and zest until just barely combined. Stir in the milk and cream until smooth.

In a separate bowl, beat the egg whites until they hold soft, medium peaks. Fold into the custard mixture.

Pour the custard mixture into a 10-inch round cake pan and set into a larger pan filled with 1-inch of water. Bake at 350°F for about 50 minutes or until the custard is just set. Let cool to room temperature.

To serve, spoon a portion of custard onto each plate and garnish with mint. This lemon custard is especially good with a garnish of ripe summer berries.