Preheat oven to 350 degrees F. Grease and flour a 12-cup bundt cake pan, leaving 2 inches at the top for the cake to rise.
In a large bowl, cream butter and sugar together until fluffy. Add eggs, one at a time; beat until fully incorporated.
In a heavy saucepan over low heat, melt chocolate bar or chocolate chips; stirring until smooth. Remove from heat. Learn different techniques for How To Melt Chocolate.
To the melted chocolate, add chocolate syrup and butter-sugar mixture; stir until well mixed.
Add 1/2 the milk mixture to chocolate mixture. Add 1 1/2 cups flour, mixing well. Add remaining milk mixture and remaining 1 1/2 cups flour; beat until well incorporated. Pour into prepared bundt pan.
Bake approximately 1 hour 20 to 30 minutes or until a toothpick inserted in the center come out clean. Cake is done when the internal temperature registers approximately 205 to 209 degrees F. on your cooking thermometer.
Remove from oven and cool 15 minutes on a wire rack; remove from pan and invert onto a cake plate. If desired, sprinkle with sifted powdered (confectioner's) sugar over the top of the cake.
Makes 16 servings.
* Learn how to make a Buttermilk Substitution.
Uncle Jimmy's Chocolate Pound Cake Recipe: https://whatscookingamerica.net/cake/chocpoundcake.htm