1. Line a very large baking sheet with foil; coat foil with cooking spray. Set baking sheet aside.
2. In a large microwave-safe bowl, combine sugar, corn syrup, almonds, and salt. Microwave on 100% power (high) for 6 minutes, stirring every 2 minutes (bowl will be hot; use oven mitts when touching bowl). Add cinnamon, vanilla, and butter. Microwave for 3 minutes more, stirring once halfway through cooking. Stir in baking soda (mixture will become foamy). Carefully pour mixture onto prepared baking sheet, spreading to 1/4-inch thickness. Cool about 20 minutes, then break into pieces.