Preheat oven to 400°F (200°C) and lightly grease a baking sheet with cooking spray.

Place cubed butternut squash and potatoes on the prepared baking sheet.

Bake for 15 minutes and set aside.

Heat olive oil in a heavy-bottomed saucepan over medium-high heat.

Add diced onion and minced garlic and sauté until onion is translucent (about 7 minutes).

Add flour and mix thoroughly, cooking while stirring constantly to prevent burning until a thick paste forms (2-3 minutes).

Pour vegetable broth into the onion-flour mixture and whisk vigorously until the mixture thickens and boils (about 7 minutes).

Add vegan Worcestershire sauce, salt, pepper, oregano, and thyme.

Pour in water and reduce heat to a simmer.

Add the baked squash and potatoes and cook over medium heat until fork-tender (about 10 minutes).

Add frozen mixed vegetables and cook until heated through (3-4 minutes).

Pour the vegetable mixture into a large baking dish.

Roll out the vegan pie dough to fit the baking dish and lay it on top, making a few cuts to allow steam to escape.

Bake until the filling is bubbling and the crust is browned (about 30 minutes).