You can substitute the peppermint tea with 1 tablespoon of peppermint extract, adding the extract in after the chocolate cooks with the vanilla extract.
Spray an 8-by-8-inch baking pan with nonstick cooking spray and line with a piece of parchment paper or foil, then grease the parchment with butter.
In a medium saucepot set over medium heat, add the cream, milk, and teabags. Cook the mixture until little bubbles form around the edges of the pan, about 10 minutes. Turn off the heat and steep the teabags for 10 minutes. Remove the teabags from the liquid and squeeze dry (being careful to not burn yourself).
Mix the sugar, cocoa powder, molasses, and salt into the liquid. Return the pot to medium-high heat and bring the mixture to a rolling boil, then cook until a candy thermometer inserted in the mixture (but not touching the bottom of the pot) reaches 234 degrees F, about 10 minutes.
Remove the pot from the heat and add the butter and the vanilla without stirring. Cool at room temperature until the candy thermometer reads 110 degrees F, about 20 minutes.
Stir the chocolate until the mixture is matte and no longer shiny. Pour the chocolate into the prepared pan and cool until solid. Cut into squares and then serve.