Preheat your oven to 350°F (175°C). Line a sheet pan (about 15×10 inches) with parchment. Yes, this is a roll, not a cylinder—think flat to roll later.

Separate the eggs. Beat the yolks with 1/4 cup of sugar and vanilla until pale and thick. You’re making a little sunshine here.

Beat the egg whites with the remaining 1/4 cup sugar until stiff peaks form. It should look glossy and hold its shape like a victory pose.

Fold the sour cream into the yolk mixture, then sift in flour, baking powder, and salt. Gently combine—no swirls of overmixing, please.

Fold a third of the whipped egg whites into the batter to lighten it, then carefully fold in the rest until no white streaks remain. It should be airy and speckled with strawberry bits.

Spread the batter evenly on the prepared sheet pan. Bake for 10-12 minutes, or until the surface springs back lightly.

Dust a clean kitchen towel with powdered sugar. When the cake comes out, invert it onto the towel—peel off the parchment gently. Roll the warm cake in the towel and let it cool completely. This shapes the roll and prevents cracking.

Whip the heavy cream with powdered sugar until stiff peaks form. Fold in chopped strawberries and jam, if using. Chill a few minutes for easier spreading.

Unroll the cooled cake carefully, spread the filling evenly, and reroll tightly. Trim the ends for a neat look if you’re feeling extra picky.

Chill briefly to set, then slice and serve. Garnish with fresh strawberries and a dusting of powdered sugar if you want that show-stopper finish.