Combine flour, baking powder and salt in medium bowl.
In large mixing bowl, cream together butter and sugar. Add in vanilla and then eggs one at a time. Blend in milk.
Add in the flour mixture half at a time and mix until well blended.
Divide batter into 4 bowls, with 1/4 going into each bowl.
Add gel food coloring to 3 of the bowls: green, purple, and orange. Mix until color is incorporated.
Spray a bundt pan with non-stick cooking spray. Spoon batter into the pan my dropping spoonfuls of alternating colors of batter around the pan until all the batter has been used.
Bake for 45-50 minutes and toothpick test comes out clean.
Mix powdered sugar and milk until you get the consistency you like. Start with ½ cup powdered sugar and a few tablespoons of milk. Add more sugar and little milk until the icing is the thickness you want.
Drizzle icing on top of the bundt cake. Sprinkle the top with mardi gras sprinkles of choice.