Steps
- Line an 8in / 20cm square pan with parchment. Combine 1 cup of sugar, 1 cup of brown sugar, and 1 cup of heavy cream in a large microwave-safe measuring cup.
- Use a measuring cup with at least 2-liter capacity. Microwave at full power in a 1000-watt microwave for 4 minutes, stir, then cook for another 4 minutes.
- Add 1 teaspoon of vanilla extract and 1 tablespoon of unsalted butter. Beat with an electric mixer on high for about 2 minutes, until thick and no longer glossy.
- Spread evenly in the pan, cover, and refrigerate for about 30 minutes, until firm. Lift out and cut into squares.