Line an 8-inch square cake pan with parchment paper with a 2 inch overhang of paper on all sides.

Melt 4 tablespoons butter in a medium saucepan over medium-high heat. Add the brown sugar, vanilla, and the ½ cup cream. Bring to a boil. Let boil for 2 minutes, stirring constantly. Add the Sunbutter and stir until smooth. Take off the heat and let cool for 5 minutes.

Put the Sunbutter mixture in a mixer preferably fitted with a paddle attachment. Mix on medium-low speed and gradually add the powdered sugar. Mix until everything is incorporated and smooth. Put the mixture in the prepared pan and smooth the top with a spatula.

In a small saucepan, melt the remaining 1 tablespoon butter with the corn syrup and chocolate chips. Add the remaining 3 tablespoons of cream and mix until smooth. Pour over the top of the Sunbutter fudge and refrigerate until firm, at least 2 hours.

Cut into small squares and serve.