Preheat your oven to 375°F (190°C). Line a jelly roll pan with parchment paper, ensuring it overhangs for easy removal later.

In a bowl, whisk together the flour, baking powder, salt, and lemon zest. In another bowl, beat the eggs and sugar until light and pale, then gently fold in the dry ingredients until just combined.

Spread the batter evenly in the prepared pan and bake for 12-15 minutes, or until it turns golden brown. Keep a close eye to avoid overbaking!

Once baked, invert the cake onto a clean towel dusted with powdered sugar and let it cool completely to prevent cracking while rolling.

In a mixing bowl, combine softened cream cheese and powdered sugar. Gently mash the blackberries into the mixture, leaving some chunks for texture.

Spread the filling evenly over the cooled cake. Roll the cake into a log shape using the towel as a guide, then wrap in plastic wrap and chill in the fridge before serving.