...how much chocolate syrup?
I've made a Peppermint Ribbon Cake, when it is baked, it has a red "ribbon" swirling through it. You make the cake mix like regular, then take out 1 cup in a small bowl. In the small bowl, I added red food color and peppermint extract (since it was a peppermint ribbon in it). I'm sure that is the best way to make any cake mix "marbled". Just add about a tablespoon or two of chocolate syrup, to the small bowl (stir well). Pour little batter on top of the regular batter, and swirl in with the rest of the batter when in the pan. Bake normal. Hope this helps.
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