1. Preheat the oven to 425F. Unfold the pastry and place it on the counter. Cut a one-inch rim around the edge of the pastry. Dock the inside the rim with the tines of a fork. Transfer the pastry to non-stick baking sheets.
2. Bake until golden brown and puffed, about 20 minutes.
3. Divide the caramelized onions between the 2 tarts. Arrange vegetables over onions and top with Saga® Classic Blue Brie and vegetables. Return the tart to the oven and heat until cheese melts.
4. Bake until pastry puffs and browns, about 15 minutes. Remove and serve while hot.