Preheat your oven to 350°F (175°C). Line a 10x15-inch jelly roll pan with parchment paper and lightly grease it.

In a medium bowl, whisk together 1 cup of flour, 1 teaspoon of baking powder, and a pinch of salt.

In a large bowl, beat 4 eggs and 1 cup of sugar on high speed for 5-6 minutes until thick and fluffy. Fold in 1 teaspoon of vanilla, then add the dry mixture gradually.

Divide the batter into four bowls, tint each with gel food coloring (pink, blue, yellow, green).

Fill piping bags with colored batters and pipe horizontal stripes side by side in the prepared pan.

Bake for 10-12 minutes. The surface should spring back and be golden when done.

Invert the baked cake onto a kitchen towel dusted with powdered sugar. Roll it tightly in the towel and let cool for about 45 minutes.

For the filling, beat 8 ounces of cream cheese, 1 cup of powdered sugar, and 1 teaspoon of vanilla until smooth. Whip 1 cup of heavy cream to stiff peaks and fold into the cream cheese mixture.

Once cooled, unroll the cake and spread the filling evenly. Roll it back up tightly and refrigerate for at least 1 hour.

After chilling, spread whipped frosting over the outside if desired, and top with pastel sprinkles. Slice to serve.