Preheat oven to 325 and grease the muffin tins or pustie tins.
To Make the Sweet Dough:Put the flour and orange zest in a large mixing bowl. Cut the butter into small 1/2 inch chunks and add to flour. Using your fingertips and thumbs, work the butter into the flour. Work the butter in for just a minute or two so that it is mostly incorporated, but you will still be able to see some of the little chunks of butter among the flour. Just make sure they are smaller than pea-sized.Mix eggs, sugar and salt. Add to flour/butter mixture. Stir until a uniform dough is just formed. Turn the dough onto a lightly floured board, and form into a round disk about 5 inches in diameter. Cover in plastic wrap and refrigerate for 30 minutes.
Meanwhile, to make the filling: In a large mixing bowl, add marmalade, vanilla, cherry preserves, chopped walnuts, and liqueur. Stir to combine. Set aside.
Next, remove dough from the fridge, discard plastic wrap, and put the dough on a lightly floured board. Using a rolling pin, roll out the dough to about 1/2 inch thick. Use a cookie cutter, glass or large ravioli cutter to cut out 3 ½ inch rounds for the filling and 2 ½ inch rounds for the top, an equal number of each.
Hold a 3 ½ inch dough round in the palm of your hand and fill with 1 heaping tablespoon of filling.
Place one of the smaller rounds on top and pinch to seal. Now you have a cute little tart!(Note) If you are using the pustie tins, place the large dough round in first, press gently into the scalloped shape. Add the filling and then place on the 2 ½ inch round. Pinch to seal. For an optional added bonus: Before baking, I like to make a little heart-shaped piece of dough and place it top before baking. Another option is to put a dab of filling on top before baking.Bake for 25 minutes until golden brown. Cool before serving - if you can wait!