This cake, bursting with berries, is perfect for a picnic.

Active time: 30 min Start to finish: 2 hr

1 stick (1/2 cup) unsalted butter
1/4 cup heavy cream
3 large eggs at room temperature
1 1/4 cups granulated sugar
1/2 teaspoon salt
2 teaspoons finely grated fresh lemon zest
2 teaspoons baking powder
1 teaspoon vanilla
2 1/2 cups cake flour (not self-rising)
6 cups mixed berries (1 3/4 lb) such as raspberries, blackberries, and blueberries
2 tablespoons confectioners sugar

Preheat oven to 350°F. Grease a 13- by 9- by 2-inch metal baking pan, then line bottom with wax paper and grease paper.

Heat butter with cream in a small saucepan over low heat until melted, then cool.

Beat eggs, granulated sugar, and salt with an electric mixer on high speed until mixture is thick, pale, and forms a ribbon when beaters are lifted, about 5 minutes with a standing mixer or about 12 minutes with a handheld. Add zest, baking powder, and vanilla and mix on low speed until blended.

Add 1 1/4 cups flour and half of butter mixture and mix on low speed until blended. Mix in remaining butter and 1 1/4 cups flour in same manner. Increase speed to medium and beat 1 minute with a standing mixer or 2 minutes with a handheld, or until batter is thick and sticky. Add berries and carefully fold in with a rubber spatula until barely combined. (Raspberries will begin to fall apart, and batter will look slightly pink.) Spoon batter into baking pan, gently smoothing top. Bake in middle of oven until springy to the touch and a tester inserted into center comes out clean, 45 to 50 minutes. Cool completely in pan on a rack.

Run a knife around edge of cake, then invert rack over cake and flip cake onto it. Remove wax paper and reinvert onto a platter.

Just before serving, dust with confectioners sugar