Line an 8-inch square baking pan with parchment paper, ensuring an overhang for easy removal later.

In a medium saucepan, combine ½ cup unsalted butter, 1 cup brown sugar, and ¼ cup heavy cream. Set the heat to medium-low and stir continuously until the mixture is smooth and bubbly, about 5 minutes.

Remove from heat and stir in 1 cup of creamy peanut butter and 1 teaspoon of vanilla extract until glossy.

Gradually add 2 cups of powdered sugar, stirring continuously until fully incorporated.

Transfer the mixture to the prepared baking pan and smooth the top evenly.

Sprinkle a pinch of flaky sea salt over the top before it sets.

Chill in the refrigerator for 2 to 3 hours until firm.

Lift out of the pan using the parchment overhang and cut into squares.