2 1/2 cups all purpose flour

3/4 cup butter (softened)

1 1/2 cups sugar

3 eggs

1 1/2 tsp. vanilla extract

1/4 tsp. baking soda

3/4 cup milk

2 tsp. baking powder

1/2 cup chocolate syrup 

Preheat oven to 350 degrees.

1. In a large bowl, beat together the butter, sugar, eggs and vanilla with an electric mixer, until smooth and creamy. Add a little bit of milk at a time and keep beating.

2. in another bowl, stir together the flour and baking powder. Add to the milk mixture  and beat until everything is combined.

3. Grease a large bundt pan and pour about 2/3 of the batter into the pan.

4. Add the chocolate syrup and the baking soda into the remaining batter, and beat with the mixer until blended.

5. Spoon the chocolate batter into the pan over the white batter.

6. Using a spatula or knife, gently swirl the two batters together to give a marble look.

7. Bake for 60 to 75 minutes, until a toothpick stuck into the the cake comes out clean.

8. Allow the cake to cool for about half an hour before removing  from the pan.