Make the Lemon Curd

1. In a medium sauce pan over low heat, whisk together butter, sugar, lemon juice, zest and salt until combined.
2. Add eggs one at a time, whisking until fully mixed each time.
3. Cook over low heat about 8-9 minutes, whisking frequently, until somewhat thickened. Remove from heat and cool completely. Chill in the fridge until ready to use.

Make the Tart

1. Preheat oven to 375˚F. Line a cookie sheet with parchment paper and lightly dust with flour.
2. Place puff pastry sheet on top of the dusted paper. Being careful not to cut completely through the pastry, slice a 1/2 inch edge all the way round. Poke the puff pastry in the middle a few times with a fork.
3. Bake pastry 14 -15 minutes, until puffed and golden. Remove from heat and gently press the center down. Let cool about 10-15 minutes until around room temperature.
4. While pastry is cooling, beat mascarpone, cream cheese, lemon juice and vanilla together with an electric mixer until smooth. Sift in powdered sugar and beat again until smooth.
5. Gently spread mascarpone mixture in a thin layer on top of the puff pastry.
6. Top with berries as desired. Drizzle with cooled lemon curd and garnish with fresh mint.