In a medium bowl, whisk the egg yolks and sugar together until pale and thick.
In a medium saucepan, combine the egg yolk mixture, milk, cream, and bay leaves. Heat gently over medium-low to low heat, stirring constantly, until the custard thickens enough to leave a velvety coating on the back of a wooden spoon. (If you are using a thermometer, the custard should reach about 175°F.) Do not let the mixture boil or it will curdle. Remove it from the heat as soon as you have obtained the right thickness and continue stirring for 2 more minutes. Leave the bay leaves in the custard while it cools, then remove them.
Place the berries in dishes, pour the custard over, garnish with bay leaves, if desired, and serve.