1-First Step: Preparation: Preheat your oven to 350°F (175°C). Prepare two roll cake sheet pans by greasing them with butter and lining with parchment paper. Gather all ingredients, ensuring eggs and milk are at room temperature; this helps with better batter texture and volume.

2-Second Step: Make the Vanilla Sponge Batter: In a mixing bowl, whisk 4 egg yolks with half of the caster sugar (about 5½ tablespoons) until the sugar dissolves. Add 6 tablespoons of milk, 6 tablespoons of vegetable oil, and 1½ teaspoons vanilla extract, mixing until smooth.

: In a separate bowl, sift ½ cup all-purpose flour with 6 tablespoons cornstarch and 1 teaspoon cream of tartar. Fold these dry ingredients gently into the wet mixture.

3-Third Step: Whip Egg Whites for Vanilla Sponge: Beat the 4 egg whites with the remaining caster sugar (5½ tablespoons) and 1 teaspoon cream of tartar until stiff peaks form. Carefully fold the egg whites into the vanilla batter to keep the batter light and airy.

4-Fourth Step: Prepare the Chocolate Sponge Batter: Repeat the process for the chocolate sponge: whisk 4 egg yolks with half the sugar until dissolved. Add milk, vegetable oil, and vanilla extract.

: Sift together ½ cup all-purpose flour, 6 tablespoons cornstarch, 4 tablespoons cocoa powder, and 1 teaspoon cream of tartar. Fold dry ingredients into the wet mix.

: Whip the 4 egg whites with the remaining sugar and cream of tartar until stiff, then gently fold into the chocolate batter.

5-Fifth Step: Baking: Pour vanilla sponge batter into one prepared pan and chocolate batter into the other.

: Bake both for 10-12 minutes or until golden and springy to the touch.

: Immediately invert cakes out onto parchment dusted with powdered sugar; carefully roll while warm to avoid cracking.

: Allow cakes to cool completely before unrolling to assemble.

6-Sixth Step: Prepare Strawberry Icing: Beat 2 cups softened butter until creamy. Gradually add 8 cups powdered sugar and mix thoroughly. Add ¼ cup milk, 1 teaspoon vanilla extract, ¼ cup freeze-dried strawberry powder, and pink food coloring to desired shade. Mix until smooth and fluffy.

7-Seventh Step: Assemble the Cake: Unroll both cooled sponge cakes gently. Spread the strawberry icing evenly on one sponge layer. Roll the cakes vertically together, creating the signature Neapolitan effect of vanilla and chocolate sponges with the strawberry cream inside.

8-Final Step: Add Chocolate Ganache: Heat 1 cup heavy cream until just simmering, then pour over 1½ cups chocolate chips. Let sit for a minute, then stir until smooth. Spread the ganache over the entire roll cake to finish.

: Refrigerate the assembled cake for at least 1 hour to set before slicing and serving. For variations in dietary needs, substitute plant-based alternatives or gluten-free flours as mentioned earlier.