Preheat the oven to 190°C. Line a large baking sheet with parchment paper.
Mix the pesto with the mint, garlic and lemon zest. Add a couple of pinches of chilli flakes, if liked.
Unroll the pastry and cut out 8 cm rounds or squares. Make a border with a blunt knife by drawing an inner circle or square. Using a fork, poke the base, then brush with some pesto (up to the border line).
Mix the beans with the remaining pesto and spoon over the tartlets (up to the border line).
Put the tartlets onto the baking sheet and put it in the oven for 10-15 minutes until the edges are golden.
Serve the tartlets warm or at room temperature, with mint leaves scattered on top.