Prepare a double boiler. Melt chocolate until smooth.

Line a cupcake pan with 5 paper liners.

Drop a spoonful of chocolate into each liner and spread evenly on the bottom (keep some chocolate to the top of the toffee nut cups).

Freeze to harden.

Combine butter and monk fruit sweetener in a saucepan over a medium heat, stirring until sweetener is completely dissolved completely.

Once the mixture starts to thicken, add the chopped walnuts.

Remove the chocolate cups from the freezer and fill each cup with a half spoon full of toffee mixture, working quickly before the toffee hardens.

Drizzle remaining melted chocolate on top and sprinkle with sea salt.

Freeze for an additional hour and serve.