Prepare the Cake Batter – Preheat oven to 350°F and line three 6-inch cake pans with parchment paper. Whisk together flour, baking powder, and salt in one bowl. In another bowl, cream butter and sugar until light and fluffy. Add eggs, vanilla, yogurt, and buttermilk, mixing until smooth. Gradually combine the dry ingredients with the wet mixture until fully incorporated.

Create the Ombre Layers (Optional) – Divide the batter evenly into three bowls. Add green food coloring in varying amounts for an ombre effect. Pour each batter into a separate cake pan and bake for 20-30 minutes, or until a toothpick inserted comes out clean.

Cool and Prep for Frosting – Let cakes cool for 10 minutes before inverting onto a wire rack. Wrap each cake layer in plastic wrap and freeze for at least one hour before frosting.

Make the Vanilla Buttercream – Whip butter until fluffy, then slowly add powdered sugar. Mix in vanilla extract, then beat on high speed for 2-3 minutes. If needed, add heavy cream for a smoother consistency.

Assemble the Cake – Stack the cake layers with buttercream frosting between each. Coat the entire cake in a smooth layer of frosting.

Add the Ganache Drip – Freeze the frosted cake for 10 minutes. Melt white chocolate with heavy cream and drizzle down the sides for a beautiful drip effect.

Garnish with Lucky Charms Marshmallows – Decorate the top with colorful marshmallows for a festive touch.