Beat butter at medium speed with an electric mixer until creamy. Gradually add sugar, beating until light and fluffy. Add eggs, 1 at a time, beating just until blended after each addition.
Stir together flour and baking soda. Add to butter mixture alternately with sour cream, beating at low speed just until blended, beginning and ending with flour mixture. Stir in vanilla. Use batter immediately, following baking directions in "Pick a Pan," below.
Chocolate-Red Velvet Cake Batter: Prepare Sour Cream Cake Batter as directed, stirring 3 tablespoons unsweetened cocoa into the flour mixture. After preparing batter as directed, stir in 2 (1-ounce) bottles red food coloring. Use batter immediately, following directions for desired cake.
Sour Cream-Pecan Cake Batter: Prepare Sour Cream Cake Batter as directed, substituting 1 1/4 cups firmly packed brown sugar and 1 1/4 cups granulated sugar for 2 1/2 cups sugar. After preparing batter as directed, stir in 1 1/2 cups chopped, toasted pecans. Use batter immediately, following directions for desired cake.
Cranberry-Pecan Cake Batter: Soak 1 (6-ounce) package sweetened dried cranberries in boiling water to cover for 10 minutes. Drain well, and press gently between paper towels. Pulse 4 to 5 times in a food processor or until finely chopped. Prepare Sour Cream Cake Batter as directed. Stir finely chopped cranberries; 1 cup finely chopped, toasted pecans; and 2 tablespoons grated orange rind into prepared cake batter. Use batter immediately, following directions for desired cake.
Lemon-Poppy Seed Cake Batter: Prepare Sour Cream Cake Batter as directed; stir in 3 tablespoons grated lemon rind and 2 tablespoons poppy seeds. Use batter immediately, following directions for desired cake.
Pick a Pan: Sour Cream Cake Batter can be baked in lots of different shapes and sizes--just use these times as a guideline, and be sure to grease and flour your pans. With smaller muffin pans and molds, we found it easier to use a vegetable cooking spray with flour. Check for doneness at the minimum time range, continuing to bake until a wooden pick inserted in the center comes out clean. Variations with added fruit and nuts will require the maximum time and yield more mini cakes.
Bake at 325° in 1 (12-cup) tube pan for 1 hour and 15 minutes to 1 hour and 30 minutes.
Bake at 325° in 3 (8- x 4-inch) loaf pans for 55 to 65 minutes.
Bake at 325° in 7 to 9 (5- x 3-inch) loaf pans for 25 to 35 minutes.
Bake at 325° in baby Bundt pans for 25 to 30 minutes. Makes 14 to 16 baby Bundt cakes. (Spoon 1/2 cup batter in each 1-cup mold.)
Bake at 350° in muffin pans 23 to 28 minutes. Makes 32 to 38 cupcakes.
Bake at 350° in miniature muffin pans for 9 to 11 minutes. Makes about 9 to 10 dozen cupcakes.