Step 1

Preheat the oven to 400°F. In a large skillet, melt the butter. Cook the onions and mushrooms until tender, about 5 to 7 minutes. Add the garlic, herbs, salt, and pepper, then cook for another 30 seconds.

Step 2

Add the flour and mix until fully dissolved. The onions and mushrooms should be coated and creamy.

Step 3

Add the broth, non-dairy milk, and frozen vegetables.

Step 4

Simmer until thick, about 12 to 15 minutes, stirring constantly. If the mixture seems too thin, simmer for a few more minutes. If the mixture seems too thick, add a bit of broth or non-dairy milk. Keep in mind that the gravy will thicken as it cools.

Step 5

Transfer the vegetable-gravy mixture into a greased deep pie dish.

Step 6

Add the puff pastry dough on top of the vegetable filling. You can trim the dough (which is square) to fit the circle pie dish, if you’d like. Press the edges of the dough with a fork and cut at least two slits into the top.

Step 7

Bake for 40 to 45 minutes, or until the puff pastry is golden brown and the filling is bubbling. Garnish with fresh herbs, if you'd like. Let cool slightly, then serve warm.