Make the marshmallows according to the directions, but replace the peppermint extract with vanilla extract. These will need to be made a day ahead in order to dry out properly. Cut the marshmallows into 1/2 inch chunks and place on a cookie sheet lined with parchment paper. Place in the freezer for at least 3 hours.
Line a 9x13 baking pan with parchment paper.
In a large saucepan over medium heat, whisk together the cream and sweeteners. Bring to a boil and then reduce the heat and simmer gently for 30 minutes. Watch carefully as you want it to simmer but not continue to boil. There should be little bubbles along the edges the whole time.
Remove from heat and add the butter, chopped chocolate, and vanilla extract. Let sit 5 minutes, until the butter and chocolate have melted, then whisk until smooth.
Working quickly, stir in the frozen marshmallows and the pecans. Spread the whole mixture evenly into the prepared pan. Refrigerate until firm, about 3 hours, before cutting into squares.
Please refer to the blog post for detailed recipe notes.