First, prepare the green shamrock cake. Preheat the oven to 350F.

In the bowl of a stand mixer, combine the flour, baking powder, baking soda, salt, and sugar. Add in the butter, and beat on low until it's incorporated and has a sandy texture.

In a small bowl, whisk together the oil, eggs, sour cream, and vanilla, and add them to the dry ingredients. Mix until combined.

Finally, pour in the milk, and beat on medium-low until smooth and creamy. Add in the food coloring, adding more or less as needed to reach desired hue.

Line a quarter sheet pan (13x9) with parchment and spray with nonstick spray. Pour the batter on top and smooth out, then bake for 20-25 minutes, until lightly golden brown, and a toothpick inserted in the center comes out clean. Let cake cool completely before handling.

When cooled off, use a medium shamrock cookie cutter and cut out as many as possible from the green cake.

Now, make the chocolate cake batter. Preheat the oven to 350F, and spray a bundt pan very well with baking spray.

In medium bowl, whisk together flour, cocoa, baking powder, baking soda, and salt.

In a measuring cup, mix together milk and vanilla.

In a stand mixer, at low speed, beat butter and sugar till blended. Increase speed to high and beat for 2 minutes. Reduce speed to medium-low and add eggs one at a time, beating well after each addition.

With mixer at low speed, alternatively add the flour mixture and the milk mixture, starting and finishing with the flour. Beat until batter is smooth, occasionally scraping bowl with a spatula. Finally, stir in the chocolate chips.

Pour about half of the chocolate cake batter into the bundt pan, then place the shamrock cakes into the pan UPSIDE DOWN, very close together. Pour in the rest of the chocolate batter. Slam the pan onto the counter a few times to make sure the batter gets all around the shamrocks.

Bake for 55-65 minutes, until a toothpick inserted in the center comes out clean or with just a few moist crumbs. You may have to cover the pan with foil and let it continue baking for 10-15 minutes if the top is getting hard but the inside is still soft.

Let the cake come to room temperature, then turn out of the pan onto a plate. Enjoy!