1. Preheat oven to 200ºC/400ºF (fan).
2. In hot skillet add a tsp of oil and both burgers, cook on each side for 2 minutes and remove from heat.
3. In the same pan add the baby spinach and cook for 1-2 minutes until wilted, remove and place spinach in strainer to allow excess liquid to run off. Let spinach cool for a few minutes and then squeeze out excess water this will help avoid being soggy.
4. On cutting board, roll out puff pastry, cut off a couple inches so it’s squared and will completely wrap the wellington. Place one cheese slice in the middle then the burger and layer with one slice of cheese, sliced onion and squeezed spinach. Then top with second burger and sliced cheese.
5. Begin to wrap pastry from one side and then the other and close the gaps on the other sides to enclose the layered burgers. Cut off excess pastry if needed.
6. Place the wrapped burgers onto a parchment lined baking sheet, fold sides down. Brush entirety with melted plant-based butter.
7. Bake for 20 – 30 minutes until golden brown.
8. For the Sauce, in a small bowl add ½ mustard sauce and ½ Oatly Crème Fraiche and whisk together, simple.
9. Remove Wellington from oven and allow to cool for 5 – 8 minutes before slicing.
10. Serve.

Subs:
Feel free to use Dijon or any spicy mustard or Sriracha mixed with mayo as the sauce works great!