Preheat oven to 350°F (175°C). Grease a 10x15-inch jelly roll pan, line with parchment paper, and grease the parchment.

Beat the eggs on high speed for 3 minutes until frothy. Gradually add the granulated sugar and continue beating for 4-5 minutes until thick and pale. Beat in vanilla.

Whisk together cake flour, baking powder, and salt. Sift over the egg mixture in two batches, gently folding with a spatula until just combined. Fold in the melted butter.

Spread batter evenly into the prepared pan. Bake for 10-12 minutes until the top springs back lightly.

Lay a clean kitchen towel flat and dust generously with powdered sugar. Immediately invert the hot cake onto the towel. Peel off parchment paper.

While still hot, roll the cake and towel together starting from the short end. Place on a wire rack to cool completely (about 1-2 hours).

Make the filling: Whip heavy cream, powdered sugar, vanilla, and pudding mix until stiff peaks form. Set aside.

Make the frosting: Beat softened butter until creamy. Add powdered sugar, vanilla, and cream. Beat until fluffy, then tint with light blue gel coloring.

Unroll the cooled cake. Spread the whipped cream filling evenly, leaving a small border. Roll the cake back up without the towel.

Frost the outside of the cake with the blue buttercream, creating rustic swirls. Top with a line of chocolate shavings and nestle the candy eggs on top. Chill for 1 hour before slicing.