Makes 12 to 18 muffins.

1 cup granulated sugar
1/2 cup butter
4 egg yolks
1 vanilla bean, split, or 1 teaspoon vanilla extract
1 cup sour cream
1/4 cup poppy seeds
8 1/2 ounces cake flour
1/2 teaspoon baking powder
1 teaspoon baking soda
6 egg whites
1/4 teaspoon cream of tartar
1 to 2 pints raspberries

Preheat oven to 315 degrees F. Grease and flour muffin tins.

Mix together butter and sugar in a mixer on second speed. Add split vanilla bean (or 1 teaspoon vanilla extract) into egg yolks. Slowly add yolks, one at a time, to butter/sugar mixture. Beat until mixture is a soft lemon color. Stir in sour cream and poppy seeds.

Sift the dry ingredients together and add into egg yolk mixture.

In a separate bowl, beat egg whites, sugar and cream of tartar until stiff. Fold into egg yolk mixture. Gently stir in 1 to 2 pints of fresh raspberries. Bake in greased muffin tins for 20 to 25 minutes.