Preheat the oven to 350 degrees F. Grease and flour a 12-cup (10 inch) Bundt pan. I used flour added baking spray and the cake stuck, so make sure you grease it well. If you are using a black Bundt pan, use 325 degrees F.
Mix together the flour, only 1 teaspoon of the baking soda, and the salt; set aside.
Beat butter, sugar and vanilla, using high speed of an electric mixer, until light and fluffy. Add eggs one at time, beating 30 seconds after each egg. Stir in flour mixture and milk, alternating between the two so that you add the flour in 3 parts. Don’t overbeat the batter, but make sure it’s thoroughly mixed.
Measure out 2 cups batter and put it in a medium bowl; stir in syrup and remaining 1/4 teaspoon baking soda and the chocolate chips (if using).
Pour vanilla batter into pan, then pour chocolate batter on top of it. The vanilla batter will bubble up over the chocolate to give you the swirl, so don’t mix it.
Bake 60 to 70 minutes (I baked for 70) or until wooden pick inserted in center comes out clean. Cool l5 minutes; remove from pan to wire rack. Cool completely; glaze or frost as desired.
Chocolate Ganache Glaze:
In a small saucepan, bring the cream to a boil. In a heatproof bowl, combine the remaining 3 ounces of chopped chocolate with the corn syrup and butter. Pour the hot cream over the chocolate and let stand until melted, about 5 minutes. Whisk until smooth. Let the ganache glaze cool until thick but still pourable, about 5 minutes.
Pour the ganache over the cooled cake. Let the cake stand until the glaze is set, at least 30 minutes, before serving.
If you don’t want to use the recipe above, you can follow the steps above but use ¼ cup cream, a little less than 2/3 cup chocolate chips and ¼ teaspoon of vanilla. I used this second recipe today and thought it was too thick, but it tasted good and was spreadable.