1. Firstly, preheat your oven to 200°C (400°F ) and line a baking sheet with parchment paper.
2. Peel, core, and chop the apples into small pieces.
3. In a medium-sized saucepan, melt the butter over medium heat. Add the chopped apples, granulated sugar, lemon juice, cinnamon, and nutmeg. Cook for 5-7 minutes, stirring occasionally, until the apples are tender but not mushy. Add some cornstarch if the filling becomes too watery. 
4. When the apples are tender, remove the saucepan from heat and stir in the vanilla extract. Let the apple filling cool to room temperature. Do not add it to the pastry straight away because your pastry won't be flaky otherwise, and it will be difficult to work with. 
5. Roll out the puff pastry sheet on a lightly floured surface into a square or rectangle. Cut the pastry into smaller squares or rectangles, depending on your desired turnovers. I made six turnovers with one roll of puff pastry. 
6. Spoon a generous amount of the cooled apple filling onto half of each pastry square, leaving a small border around the edges. Make sure you don't overfill them. Brush the edges with a mixture of dairy-free milk and turmeric. 
7. Fold the other half of the pastry square over the apple filling to create a triangle. Use a fork to press the edges firmly together and seal the turnovers.
8. Place the turnovers on the prepared baking sheet. Brush the tops with dairy-free milk and turmeric to give them a golden brown colour when baked. Cut a steam hole into the top of each turnover with a knife.
9. Bake in the oven for 15-20 minutes or until the turnovers are puffed and golden brown.
10. Remove from the oven and let the turnovers cool for a few minutes

Dust the turnovers with powdered sugar before serving. ENJOY!