Heat oven to 350 degrees F. Grease and flour a 9 x 13-inch baking pan. Alternatively,
grease 2 (9-inch) round or square baking pans and line with parchment paper.
For the cake mix: In large mixing bowl, whisk together flour, brown sugar, cocoa
powder, baking soda and chips. Mix well to distribute and break up any sugar lumps.
Spoon into large heavy-duty resealable plastic bag. If shipping, double bag and
attach cake mix directions to bag.
To make the cake: Pour cake mix into large mixing bowl. Add oil, butter, water,
buttermilk, eggs and vanilla. Beat on low speed 30 seconds until combined. Scrape
bowl well. Increase speed to medium high and continue beating batter for 2 minutes.
Scrape bowl well.
Spoon into baking pan(s) and smooth top of batter. Bake 9 x 13-inch cake for
25-30 minutes just until tester inserted at center comes out clean. Bake 9-inch
pans for 18-20 minutes.
If frosting cake in the pan, cool cake 1 hour in pan before frosting.
For a layer
cake: Cool cakes 10 minutes in pans. Run thin spatula around cake to loosen from
pan then invert onto cooling rack. Cool 30 minutes more before frosting.
Baker's hint: This batter also makes 24 cupcakes. Bake for 12-15 minutes.
Nutrition values per serving: 189 calories, 8 g fat (3 g saturated fat),
28g carbohydrates, 1 g fiber, 3 g protein, 28 mg cholesterol, 149 mg sodium