Instructions

1. Preheat oven to 350 F (175 C).
2. In a small saucepan over medium heat, melt ½ cup (125 ml) butter. Cook, stirring occasionally, until butter stops foaming and solids start to turn golden brown, 8 to 10 minutes. Transfer butter to a medium bowl and set aside to cool slightly.
3. In a medium bowl, stir gingersnap cookie crumbs, salt and ⅓ cup (80 ml) browned, melted butter until well combined and mixture sticks together in a clump when pressed between fingers. Press crust mixture into a 9-in (23 cm) fluted tart pan, pressing mixture evenly into bottom and up sides. Refrigerate tart shell for 10 minutes. Save any remaining browned butter for another use; it will keep in an airtight container in refrigerator for up to 2 weeks.
4. Place chilled tart shell on a rimmed baking sheet and bake until firm, 12 to 14 minutes. Set aside on a rack to cool completely at room temperature.
5. To make blackberry filling, start by placing water in a small bowl and sprinkling gelatin evenly overtop. Let bloom for 5 minutes.
6. Meanwhile, place blackberries in bowl of a food processor fitted with an S blade. Blend until blackberries are well puréed. Strain mixture through a fine-mesh strainer into a bowl and discard seeds. You should have about 1 cup (250 ml) purée.
7. In a medium saucepan over medium heat, bring milk and sugar to a simmer, stirring often. Remove from heat and stir in bloomed gelatin until it melts. Transfer warm milk mixture to a blender along with blackberry purée, whipping cream and vanilla. Blend on low until well combined. Transfer mixture to a container with a pour spout. Carefully pour blackberry mixture into crust, filling it to top. Transfer tart to refrigerator until custard is set, at least 1 hour.
8. Preheat barbecue grill to medium, taking care to clean and oil grills.
9. In a small saucepan, combine remaining ½ cup (125 ml) butter, brown sugar and Grand Marnier. Warm gently over medium heat, whisking constantly, until butter melts and sugar dissolves. Remove from heat.
10. Place orange slices on grill and baste with butter mixture. Grill until grill marks form on underside, about 1 minute, then flip and baste again. Continue to grill until warm but not falling apart. Transfer to a platter and baste one last time. Let cool for 5 minutes.
11. To serve, remove tart from tart pan and place on a serving platter. Artfully arrange grilled orange slices over tart and garnish with additional blackberries. Slice and serve.