Preheat your oven to 350°F (175°C).
Grease and flour a 13x18-inch sheet pan.
In a large bowl, whisk together the flour, baking powder, baking soda, and salt.
In a separate bowl, cream the softened butter and sugar until light and fluffy.
Add the eggs, one at a time, mixing well after each addition.
Stir in the vanilla extract and mix until combined.
Alternate adding the dry ingredients and buttermilk to the butter mixture, starting and ending with the dry ingredients.
Add in the green food coloring until you achieve your desired shade.
Fold in the rainbow sprinkles gently.
Pour the batter into the prepared sheet pan and smooth the top.
Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cake to cool in the pan for 10-15 minutes before transferring to a wire rack.
Once cool, frost with cream cheese frosting and sprinkle with additional sprinkles, if desired.