Preheat your oven to 350°F (175°C) and line a 12-cup muffin pan with colorful cupcake liners.

In a medium mixing bowl, whisk together the flour, baking powder, and sea salt until no lumps remain.

In a large bowl, cream together the softened butter and granulated sugar with an electric mixer for 2-3 minutes until light and fluffy.

Add eggs one at a time and mix well after each addition. Then stir in the vanilla extract until smooth.

Gradually add the dry mixture to the wet mixture, alternating with milk, beginning and ending with flour. Mix until just combined.

Fill the cupcake liners two-thirds full with the batter.

Bake for 18-20 minutes until a toothpick comes out clean. Cool in the pan for 5 minutes before transferring to a wire rack.

Prepare the green frosting by beating softened butter until smooth, then gradually add powdered sugar, vanilla, and milk until fluffy, adding food coloring.

Frost the cooled cupcakes generously with the green buttercream frosting.

Decorate with rainbow candy strips and sprinkle with edible gold flakes or sprinkles for the finishing touch.