Combine brown sugar, cream, and maple syrup in a large microwave-safe bowl. Cook on high in the microwave for 6 minutes.
Remove and stir for 1 minute. Cook for 6 minutes more. Let cool for 1 to 2 minutes. Add butter and vanilla extract. Beat with an electric mixer on medium-low speed until thick and light.
Pour mixture into a small pan no larger than 8x8 inches. Cut into squares before refrigerating.
