It's walnut season, which is one of the indicators that fall is upon us. The harvest begins at the end of August and ends in November. Most folks are surprised to find out that California walnuts account for 99 percent of the commercial U.S. supply and two-thirds of the world supply. Most walnuts that we eat are a hybrid of the English (Persian) walnut.

Walnuts are good for us, according to numerous studies. The walnut is the only nut that contains a significant amount of omega-3 fatty acids. So we can relax and enjoy them.

I stumbled upon this cake idea years ago when I was reading about different uses for olive oil and saw a recipe for an olive oil cake. Why not? If butter or oil would work in most cakes, why not use olive oil? Italians have been doing it for centuries.

It is important to use a good quality olive oil that has a fruity flavor with a slight biting peppery taste. A good way to find an olive oil you like is to visit a market or specialty store that has an olive oil bar for tasting. You can try out a number of different styles and varieties that can be very helpful in developing your olive oil preferences. I prefer full-bodied extra virgin oil -- a pure olive oil may be good for sauteing but won't hold up in the flavor department for this recipe -- extra virgin is the way to go here.

Olive oil and walnuts may seem like a strange dessert combination but they shine in this light, slightly fruity and very moist dessert cake. The orange juice adds a citrus component to the walnut flavor and heightens the fruity extra-virgin olive oil flavor. The cake becomes slightly crispy on the outside while remaining moist and rustic textured on the interior.

Depending upon the season I will serve the cake with a compote of fresh, sliced strawberries, oranges or even peaches. The olive oil and orange juice have a secondary benefit: keeping the cake moist up to a day after baking. In fact, this cake seems to taste better the day after it's made. Enjoy.

Walnut Olive Oil Cake

Serves 8.

6 ounces chopped walnuts

1 cup all-purpose flour

1 tablespoon baking powder

4 medium eggs

1 1/2 cups sugar

Juice of 1 medium orange, about 1/2 cup

Zest of 1 medium orange, finely chopped

1/2 cup olive oil

Powdered sugar, for garnish

Whipped cream, optional

1. Preheat the oven to 350 F. Spray a 9-inch diameter spring-form pan with olive oil spray on the bottom and sides. Process the walnuts in a food processor fitted with the metal blade, until they are finely ground, almost like bread crumbs. Combine the ground walnuts, flour and baking powder in a mixing bowl, and set aside.

2. Using an electric mixer on medium, beat the eggs until they are frothy. Gradually add the sugar and beat the mixture until it is light, thick and pale yellow, about 4 minutes. Gradually add the walnut flour mixture; then add the orange juice, orange zest and olive oil, mixing just to combine.

3. Transfer the batter into the spring-form pan; place on a rimmed baking sheet. Bake for 50 to 60 minutes or until a skewer comes out clean. Cool cake completely in pan on a rack. Release the sides of the pan. Place the cake on a serving platter and sprinkle powdered sugar in a decorative pattern on top. Slice and serve with whipped cream, if desired.

(Diane Rossen Worthington is an authority on new American cooking. She is the author of 18 cookbooks, including "Seriously Simple Parties," and a James Beard Award-winning radio show host. You can contact her at www.seriouslysimple.com.)