Preheat the oven to 350° F. Grease an 8 or 9 inch tart pan with a removable bottom or use a standard pie plate. To make the crust. In a food processor, pulse together the pretzels, butter, and brown sugar until the pretzels are fine crumbs. Press the mix into the prepared pie plate. Bake 8 minutes, until golden. Meanwhile, combine the chocolate, 1 tablespoon cream, and the coconut oil in a microwave-safe bowl. Microwave, stirring every 45 seconds, until melted. Carefully spread the melted chocolate onto the bottom of the crust and gently up the sides. Chill in the freezer for 10-15 minutes. In a medium-sized mixing bowl, beat the cream cheese and powdered sugar on high speed, until very smooth and creamy, about 2 minutes. Add the peanut butter and beat until combined. Slowly add the 1 1/4 cups heavy cream, 1/4 cup at a time until incorporated. Add the vanilla and whip on high spread until light and fluffy, about 1-2 minutes. Spoon the peanut cream into the chilled crust. Cover and chill 1 hour.Using an electric mixer, whip 3/4 cup heavy cream, 1-2 tablespoons powdered sugar, and 1 teaspoon vanilla together until soft peaks form. Dollop cream onto the pie. Dust generously with cocoa powder just before serving. Pie will keep for up to 4 days in the fridge.