Preheat oven to 180°C and line a large baking dish with parchment paper or grease well
Mix all filling ingredients together by hand, crumbling the feta well
Add oil to work surface and place a sheet of filo, brush with oil, place another sheet on top
Add filling leaving about 1cm on each side and roll vertically to the width of the dish for the bottom of the tree
Repeat with two more sheets, cutting off about 3cm of width to make them slightly smaller
Continue layering and cutting sheets progressively smaller, using half sheets around the 4th or 5th roll
Make a small roll for the base of the tree
Brush with oil, sprinkle sesame seeds, and bake for 45-55 minutes, reducing temperature to 170°C after 10 minutes
Keep filo covered with a tea towel while working as it dries quickly
Use scissors to trim rolls if too large and avoid overfilling to prevent bursting
