Preheat the oven to 375°F (190°C).

Roll out the puff pastry sheet on a lightly floured surface to fit your tart pan. Press the pastry into the pan, trimming any excess.

Prick the bottom of the pastry with a fork to prevent it from puffing up too much during baking.

Spread the frozen berries evenly over the pastry.

Sprinkle sugar over the berries, adjusting the amount based on your sweetness preference and the tartness of the berries.

Bake in the preheated oven for 25-30 minutes or until the pastry is golden brown and the berries are bubbling and juicy.

Remove from the oven and let the tart cool slightly before slicing.

Serve the Mixed Berry Tart warm, optionally with a dusting of powdered sugar or a scoop of vanilla ice cream. Enjoy your delightful berry dessert!