• Preheat oven to 400°F. Line a large baking sheet with parchment paper; set aside.

To prepare the tart shells:

• Cut the puff pastry sheet into 6 rectangles approximately 4 ¼-inches by 3-inches each. Place the rectangles on the prepared baking sheet. Score each pastry with a sharp knife, about ½-inch from the outer edge all the way around making a rectangle inside the rectangle. Don’t cut all the way through. Pierce the center of each pastry with a fork. Whisk the egg in a small bowl then brush over the outer edges of each pastry.
• Bake the pastry shells for 15 to 20 minutes or until they’re puffed and golden brown. Transfer to a rack and cool completely before filling. If needed cut around the inner rectangle with a small paring knife and press the center down lightly to create an indention. Once cooled store lightly covered at room temperature until needed.

To prepare the cream filling:

• In a small bowl combine the mascarpone cheese and powdered sugar. Beat with an electric mixer until smooth. Turn the mixer on low and slowly add the whipping cream until incorporated and the mixture starts to thicken. Increase the speed to medium and add the Grand Marnier. Increase the speed to high and beat until medium soft peaks form. This won’t take long. Cover and refrigerate until ready to assemble.

To prepare the strawberries:

• Place the strawberries in a small heat-proof bowl. Pour the Grand Marnier and sugar into a separate microwave safe bowl. Heat on high for 15 to 20 seconds or until the sugar is dissolved. Pour the hot syrup over the strawberries. Stir gently to coat. Set aside to macerate and cool for 15 minutes.

To serve:

• Divide the cream filling on top of the pastry shells. Using a slotted spoon scoop sliced strawberries over the cream. Drizzle each with a little strawberry juice and pass any remaining when serving. Dust each with powdered sugar and serve immediately.