Mix together flour, sugar and salt in the bowl of a large food processor. Cut cannabutter and butter into small chunks, add to food processor and pulse 8 to 10 times until butter is incorporated. Add in ice water, a few tablespoons at a time, until the dough just holds together, do not over mix. Gather dough and shape into a disk, wrap in plastic wrap and chill for at least an hour before proceeding.
Roll out chilled dough on a lightly floured surface (or between two sheets of plastic wrap) to about 1/3-inch thickness. Use the bottom of a glass to cut out 12 rounds a little large in circumference than the size of a muffin tin cup. Gather scraps and re-roll as needed, trying to use up all the dough. Press the dough circles into the bottom and up the sides of 12 muffins tin cups. Chill for at least 30 minutes.
While crusts are chilling, preheat oven to 400°F. Prepare filling by stirring together the brown sugar and melted butter until well combined. Mix in the maple syrup, eggs, cider vinegar and extract. Beat well so mixture stays emulsified and divide the filling between the prepared chilled crusts, filling them to about 1/4-inch from the top.
Bake for 10 minutes, reduce temperature to 350 and bake until pastry is golden brown and filling is starting to set, about 10-12 more minutes. Let cool completely before removing tarts from the muffin tin and serving.