In a large mixing bowl, whisk together the flour, sugar and salt. Use your fingertips or a pastry cutter, to cut the butter into the flour until incorporated and the butter is pea-sized. Slowly drizzle in the cold milk and stir with a wooden spoon until a soft dough forms. Form into a ball and tightly wrap in plastic wrap. Refrigerate while preparing the filling.

Whisk together all the filling ingredients in a small bowl. Set aside.

Preheat oven to 350 degrees. Line a baking sheet with parchment paper or silicone baking mat.

Take the dough out of the plastic wrap. Take two sheets of parchment paper. Place the ball in the center of one sheet and place the other sheet on top. Roll the dough out into a 8x8" square. Trim rough edges if needed. Cut the square into four 6x4.5" rectangles. Cut each rectangle in half to form two matching pieces which will serve as top and bottom of the pop tart. Transfer each halves on to the prepared baking sheet.

Take 2 tsp of filling and place in the center of 4 out of the 8 rectangles. Brush a small amount of non-dairy milk or butter around the edges. Place corresponding rectangle on top and seal the edges with a fork. Pierce each pop tart in the center three times with a fork.

Brush tops with non-dairy milk or butter. (Optional): Sprinkle a bit of sugar on top. Bake for 30 min. until golden brown.

While the pop tarts are baking, make the icing. Whisk together all ingredients until smooth and creamy. Allow pop tarts to cool completely before spreading over the icing. Finish with a sprinkle of coconut sugar.