Preheat the oven to 350℉. Grease the interior of two 8 ounce ramekins with cooking spray.
In a medium bowl, add butter and heavy cream. Whisk until evenly combined.
Add in eggs and whisk until smooth.
Add in cocoa powder and erythritol. Whisk until smooth and no clumps remain.
Divide the batter between the two ramekins and add 1 tablespoon of peanut butter to the center of the ramekin.
Place ramekins on a baking sheet and bake on the middle rack and bake for 13-15 minutes or until the edges of the cake are set and the center is slightly jiggly.
Use a butter knife and run it along the edge of the cake. You will want to remove the cake from the ramekin while it’s still hot. Flip onto a plate and serve with whipped cream and chocolate sauce.