In a medium bowl, whisk flour, sugar, baking powder and salt to combine. In a separate large bowl, add cut-up roll pieces, milk, vanilla and cinnamon; stir to combine. Let sit 15 minutes, stirring occasionally, until roll pieces begin to fall apart and get mushy.

Add flour mixture, beaten eggs and melted butter to bread pudding mixture; stir to combine. Let sit another 15 minutes, stirring occasionally, until mixture is thickened slightly.

Heat a large griddle or skillet over medium to medium-low heat (about 325 degrees F). Lightly brush with butter. Pour 1/4-cupfuls of batter onto hot griddle. Cook 2 to 3 minutes until bubbles form on top of pancakes and edges are dry; flip and cook another 2 minutes until golden brown on both sides. Transfer to a plate; repeat with remaining batter, adding more butter to griddle as needed.

Meanwhile, make the topping: Heat a medium skillet over medium heat. Add butter, apples, walnuts, cinnamon, sugar and salt. Cook, stirring often, 5 to 7 minutes until apples are softened.

Top pancakes with apple-walnut mixture, slices of Brie cheese and a drizzle of maple syrup.