Line a rimmed baking sheet with heavy-duty foil. Lightly spray foil with cooking spray and sprinkle with salt.
In a large enamel-coated Dutch oven, cook together sugar, 1 ½ cups water, and corn syrup over medium-high heat, stirring occasionally, until a candy thermometer registers 235°. Add cashews; cook, stirring constantly, until a candy thermometer registers 315°, 10 to 15 minutes. Remove from heat.
Stir in vanilla extract and baking soda, stirring vigorously for 1 to 3 more minutes until well incorporated. Pour mixture onto prepared baking sheet and let cool completely. Remove brittle from foil and break into pieces. Store at room temperature in an airtight container for up to 3 weeks.
Recipe by TeaTime Magazine at https://teatimemagazine.com/salted-cashew-brittle/