For praline: Spray rimmed baking sheet with nonstick spray. Stir sugar and 1/4 cup water in heavy small saucepan over medium heat until sugar dissolves. Increase heat to high and boil without stirring until mixture turns deep amber color, occasionally swirling pan and brushing down sides with wet pastry brush, about 7 minutes. Stir in nuts. Quickly spread nuts on prepared sheet. Cool. Chop praline into small pieces. (Can be made 1 day ahead. Store in airtight container at room temperature.).
For bread pudding: Whisk eggs, cream, sugar, 1 cup maple syrup, and vanilla in large bowl to blend. Add brioche; stir to coat. Let stand at room temperature 1 hour, stirring occasionally.
Preheat oven to 375°F Butter 13x9x2-inch baking dish. Transfer bread mixture to prepared dish. Bake until puffed and golden and toothpick inserted into center comes out clean, about 40 minutes. Cool slightly. Cut into 6 to 8 pieces. Place 1 piece pudding on each plate. Place scoop of ice cream atop pudding, drizzle with maple syrup, sprinkle with praline, and serve.