Preheat oven to 350F. Spray a bundt pan with cooking spray and flour, set aside. Whisk together the flour, cocoa, baking soda and salt.

In a standup mix, with a paddle attachment, mix together the butter and sugar. Add the eggs one at a time, mixing well after each. Alternatively add the flour, sour cream and milk, ending with the flour. Beat well for 2 min.

Pour the batter into the prepared pan. Insert the sliced Mars bars into the center of the batter, making sure they don't touch the sides or bottom of the pan. Bake for 45-50 min. until the cake sprins back when lightly touched. Let cool 15 min.

Carefully remove from pan and let cool completely.

For the glaze, melt the butter in a small saucepan, making sure it is bubbling and hot. Remove from heat and add in vanilla and chocolate chips and stir to melt. Add the corn syrup and mix well. Immediately pour over cake. Place the sliced Mars bars on top, let the glaze set and serve.