Cooks.com, but you'll find variations on the Internet. As always, experiment. The following recipe uses a German Chocolate cake mix, but you can always use your own recipe and add raisins.
Chocolate Raisin Bundt Cake
1 package German Chocolate basic bundt cake mix
1/2 cup water
1/2 cup sour cream
1/3 cup unsalted butter, softened
1/2 cup raisins
Preheat oven to 350 degrees. Lightly grease bottom only of 9 x 13 inch pan.
In large bowl, blend Packet 1 (cake mix) and next 4 ingredients until moistened. Beat 2 minutes at medium speed (portable mixer use highest speed). Fold in raisins. Pour into prepared pan. Bake at 350 degrees for 30 to 40 minutes or until toothpick inserted in center comes out clean.
Cool in pan on cooling rack.