Preheat your oven to 200°C.
Roll out the pastry and place it on a baking sheet, without removing the baking parchment.
Cut 1cm incisions along the edges of the pastry, and using a fork, prick the bottom a few times.
Spread the mascarpone over the pastry base, then season with salt and pepper.
Cut the beetroot into 3 mm thick slices and arrange on top of the mascarpone.
Brush the beetroot with olive oil, then sprinkle over the pine nuts.
Bake in the preheated oven for about 25 minutes.
Garnish with rocket and serve immediately.