Preheat & Prepare: Preheat oven to 350°F (175°C). Line a 10×15-inch baking sheet with parchment paper and lightly grease. This ensures easy removal and rolling.

Whisk the Wet Ingredients: In a large bowl, whisk eggs, honey, and vanilla until light and fluffy (about 3–4 minutes). Add sourdough starter and mix until smooth.

Sift & Combine Dry Ingredients: In a separate bowl, sift together flour, cocoa powder, baking powder, salt, and cinnamon. Gradually fold into wet ingredients, alternating with milk, until a smooth batter forms.

Pour & Spread the Batter: Pour the batter onto the prepared baking sheet and spread evenly using a spatula.

Bake: Bake for 10–12 minutes, just until the cake is set but still soft to the touch. Avoid overbaking to prevent cracks.

Prepare for Rolling: Place a clean kitchen towel over the warm cake. Roll it gently from one short end to the other with the towel inside. This helps form the perfect roll shape.

Cool Completely: Allow the rolled cake to cool for 30 minutes at room temperature.

Make the Filling: In a small bowl, combine Greek yogurt, cocoa powder, honey, and melted chocolate. Mix until smooth and creamy, then chill for 10 minutes.

Unroll & Fill: Carefully unroll the cooled cake and spread the filling evenly, leaving a small border.

Re-Roll & Set: Gently re-roll the cake without pressing too hard. Wrap it in plastic wrap and refrigerate for at least 30 minutes to firm up.

Dust & Garnish: Before serving, dust with cocoa powder or drizzle with melted chocolate.

Slice & Enjoy: Slice with a sharp knife for clean cuts and serve chilled or at room temperature.