For Cake

1. Preheat oven to 350 degrees.
2. Generously grease a 10-12 cup bundt pan with non stick cooking spray. Sprinkle with flour and turn over to remove excess. Set aside.
3. To make the chocolate syrup add sugar, cocoa powder, espresso, and honey to a small saucepan. Stirring often, bring the mixture to a bowl. Reduce heat and simmer until no lumps appear. Whisk continuously.
4. Remove from heat and stir in vanilla. Set aside to cool slightly.
5. In the bowl of a stand mixer fitted with a paddle attachment, cream together butter and sugar on medium high speed until light and fluffy, about 3 minutes.
6. Add vanilla and mix until combined.
7. Add eggs one at time until fully incorporated. Stop mixer to scrape down sides of bowl as needed.
8. In a separate bowl, whisk together flour, baking powder, baking soda and salt.
9. Add the flour to the butter and sugar mixture in three additions, alternating with the sour cream and whole milk.
10. Do not over mix. A few streaks of flour should remain.
11. Add 1/2 TBSP of flour to a small bowl. Add mini chocolate chips and toss to coat.
12. Remove bowl from mixer and gently fold in chocolate chips with a large spatula.
13. Separate 1/3 of batter into a medium bowl and stir in the chocolate syrup. Use a wooden spoon or spatula to combine completely.
14. Transfer half of the vanilla batter into the prepared bundt pan.
15. Scoop all of the chocolate batter on top and then repeat with the remaining vanilla batter.
16. Using a table knife, gently swirl 3 to 4 figure eights into the batter, being sure to reach towards the bottom of the pan and pull up during the motion.
17. Do not swirl the batter excessively or the marble will blend together rather than leaving distinct swirls.
18. Tap bundt pan firmly on countertop 2-3 times to release any air bubbles.
19. Bake for 50-60 minutes until a toothpick inserted in the center comes out clean. The cake top should be golden brown and spring back when pressed gently.
20. Cool cake on a wire rack in the pan for 25 minutes.
21. Invert the cake onto a plate or platter, tapping to release if needed.
22. Cool cake completely before adding chocolate ganache glaze.

For Chocolate Ganache Glaze

1. Heat heavy whipping cream over medium high heat in a small saucepan. Remove from heat once simmering, do not boil.
2. Add chocolate to a medium bowl and pour hot cream over the top.
3. Allow to sit for 5 minutes before whisking to combine.
4. Let ganache sit at room temperature for 10-15 minutes to thicken.
5. Pour over top of cake.