Preheat your oven to 350°F (175°C) and line your cupcake pan with paper liners. Prepare the boxed cake mix according to package instructions, combining eggs, water, and vegetable oil. Pour the batter into the liners, filling each about two-thirds full. Bake for 15-20 minutes, until a toothpick inserted in the center comes out clean. Allow the cupcakes to cool completely on a wire rack.

In a mixing bowl, beat together 1 cup of unsalted butter until creamy. Gradually add 4 cups of sifted powdered sugar, mixing at low speed. Add 2-4 tablespoons of milk and 1 teaspoon of vanilla extract, whisking until fluffy.

Divide the buttercream frosting into bowls and tint with pastel gel food coloring for a bright look. Mix thoroughly.

Use a piping bag or offset spatula to frost the cupcakes generously with the white buttercream. Arrange larger cupcakes for the head and smaller ones for ears and body.

Use piping tips to create bunny features with colored frosting. Stick candy eyes onto the cupcakes and sprinkle with shredded coconut. Add jelly beans or mini chocolate eggs around for a festive touch.

Arrange the decorated cupcakes into the desired bunny shape on a serving platter, ensuring they are close for the pull-apart effect. Gently press them together if needed.

Refrigerate the assembled cake for about 30 minutes to set the frosting. Serve this delightful cake at your Easter gathering.