Salted Spicy Peanut Brittle with Ice Cream

Line a rimmed baking sheet with parchment paper; coat with nonstick spray. Pulse peanuts in a food processor until the size of peas. Heat butter in a medium skillet over medium. Cook peanuts, stirring often, until golden, about 2 minutes. Using a slotted spoon, transfer nuts to paper towels to drain. Let cool.

Sprinkle sugar evenly across the bottom of a medium saucepan; fit saucepan with thermometer. Set over medium heat and cook, stirring with a heatproof rubber spatula, until sugar is melted and thermometer registers 290°, about 3 minutes. Continue to cook, without stirring, until deep amber in color and thermometer registers 300°, about 30 seconds longer. Mix in vinegar, baking soda, five-spice powder, cayenne, and nuts. (The mixture will begin to bubble and foam—remain calm.) Immediately pour onto prepared baking sheet and spread as thin as possible with spatula. Sprinkle peanut brittle with salt; let cool.

Crush brittle into small pieces. Scoop ice cream into bowls and top with brittle.

Do Ahead: Brittle can be made 1 week ahead. Break into large pieces and store airtight, separated by sheets of parchment to prevent sticking.