Preheat the oven to 190°C. Line 2 baking sheets with baking paper.
Cut the olives, chilli or red pepper and tomatoes to tiny bits for the tree decorations. Grate the cheese.
Roll out the puff pastry and, using a cookie cutter, stamp out mini Christmas trees. Place them onto the lined baking sheets.
Brush them the pesto, then garnish them with the vegetable bits looking like dressed Xmas trees.
Scatter some grated cheese on top of each, then bake for approx. 10 minutes until golden.
Let them cool slightly or completely before serving.