Divide berries between four 8-ounce dessert dishes or stemmed glasses.
Fill the bottom of a double boiler (or a saucepan with a metal bowl fitted snuggly on top) with 1-2 inches of water or just below bowl. Bring water to a simmer.
Beat egg yolks and sugar in top of double boiler or bowl with an electric mixer or wire whisk until fluffy and light in color, about 5 minutes. Maintain water at a low simmer while beating.
Add Marsala 1 tablespoon at a time, continuously beating until mixture forms very soft peaks, about 8 minutes.
Pour Zabaglione over berries and serve immediately
Fresh berries are an elegant addition this classic Italian wine and egg yolks dessert. Allow about 15 minutes to whisk together just before serving. In France, this dessert is known as sabayon.