Preheat oven to 350° 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 fresh raspberries. Bake in greased muffin tins for 20 to 25 minutes.Makes 4 Source: