Prepare the Croissant Dough:

1. Mix Dry Ingredients: In a large bowl, combine flour, yeast, sugar, and salt.
2. Add Liquids: Mix the warm non-dairy milk and water, then add to the dry ingredients. Mix until the dough comes together.
3. Knead the Dough: Turn the dough onto a floured surface and knead for about 5 minutes until smooth. You can also use a stand mixer with a dough hook.
4. Rest: Place the dough in a greased bowl, cover with a damp cloth, and let it rise in a warm place for 1 hour or until doubled in size.
5. Incorporate Butter: Roll out the dough into a rectangle (about 12×18 inches). Evenly distribute the chilled vegan butter cubes over 2/3 of the dough. Fold the dough into thirds (like a letter), and then roll it out again into a rectangle. Repeat this folding and rolling process 3 times, chilling the dough for 15 minutes between each fold.
6. Chill: After the final fold, wrap the dough in plastic wrap and refrigerate for at least 1 hour or overnight.

Prepare the Pistachio Filling:

1. Blend Ingredients: In a food processor, combine ground pistachios, sugar, vegan butter, non-dairy milk, vanilla extract, and almond extract (if using). Blend until smooth and creamy.

Assemble the Tart:

1. Roll Out Dough: Preheat the oven to 375°F (190°C). Roll out the croissant dough into a large rectangle (about 12×16 inches) on a floured surface.
2. Spread Filling: Spread the pistachio filling evenly over the dough, leaving a 1-inch border around the edges.
3. Form the Tart: Starting from one long side, roll the dough into a log. Slice the log into 2-inch pieces and arrange them cut side up in a greased tart pan or a baking dish.
4. Bake: Bake in the preheated oven for 25-30 minutes or until golden brown and puffed.

Finish the Tart:

1. Glaze (Optional): Warm the apricot jam and brush over the tart for a shiny finish.
2. Top and Serve: Dust with powdered sugar and sprinkle with extra pistachios. Serve warm or at room temperature.