Get out all of the ingredients and measure them.
Preheat oven to 350 degrees.
Place butter and sugar into a large mixing bowl.
Beat together butter and sugar.
Add the eggs and beat until incorporated.
Then gradually beat in flour, baking powder, and salt.
Beat in milk until smooth, then scoop out 1 ½ cups and set aside.
Fill bundt pan with ¾ cup cups of white batter and set rest aside.
Mix remaining batter with green gel coloring, and start pouring batter into the bundt pan, a little at a time, until finished. Make sure to avoid the sides of the pan.
Add remaining white batter to the bundt pan.
Take a hot spoon handle or knife and swirl batter slightly to marble the batter.
Bake at 350 degrees for 50-60 minutes or until a toothpick comes out clean and edges turn slightly golden.
Once fully baked, set aside to cool before turning out onto a plate.