Optional: diced strawberries or mini chocolate chips
👩🍳 Instructions
🔹 Prepare the Sponge:
Preheat oven to 350°F (175°C). Line a 10×15-inch jelly roll pan with parchment paper.
Whip eggs & sugar: In a large bowl, beat eggs and sugar with a mixer on high speed for 5–6 minutes, until pale and fluffy. Add vanilla.
Add dry ingredients: Sift together flour, baking powder, and salt. Gently fold into the egg mixture in batches.
Add oil and milk: Combine milk and oil in a small bowl, then fold gently into the batter to keep it airy.
🔹 Color & Pipe Design:
Scoop out 1 tbsp of batter and tint it black. Put into a piping bag (for “seeds”).
Remove about 1/4 cup and tint green. Set aside for “rind.”
Tint the remaining batter red or pink for the watermelon flesh.
Pour the red batter into the prepared pan and spread evenly.
Pipe random dots of black “seeds” across the surface.
Bake for 12–14 minutes or until the top springs back when lightly touched.
🔹 Roll & Cool:
Remove cake and immediately turn it out onto a clean tea towel dusted with powdered sugar.
Peel off the parchment, then roll the cake up with the towel (starting from the short side).
Let it cool rolled up completely—this sets the shape.
🔹 Make the Filling:
Whip heavy cream with powdered sugar and vanilla until medium-stiff peaks form.
Optionally fold in small chopped strawberries or chocolate chips for texture.
🔹 Assemble:
Carefully unroll the cake and spread the whipped cream filling evenly.
Roll it back up tightly (without the towel).
Use the green-dyed batter (baked separately or piped before) to frost one end of the roll as the watermelon rind—or dust the exterior with powdered sugar for a cleaner look.
