1 sheet frozen, store-bought puff pastry, thawed
1 1/2 cups carrots, chopped
1 cup potato, diced
3/4 cup vegetable broth
1/2 cup (1 stick) unsalted butter
1/2 onion, chopped
4 cloves garlic, minced
3 tablespoons all-purpose flour
2 tablespoons heavy cream
2 tablespoons extra-virgin olive oil
2 teaspoons dried thyme
1/2 teaspoon dried oregano
1/4 teaspoon ground mustard seed
kosher salt and freshly ground pepper, to taste
Preheat oven to 400º F.
Bring a large pot of cold, salted water to boil and cook potatoes for 8 minutes, or until tender. Drain and set aside.
In a large skillet or Dutch oven, heat olive oil over medium heat and saute carrots and onion until tender. 8-10 minutes.
During the last 1-2 minutes of cooking, add drained potatoes and garlic and cook until fragrant. Season with salt and pepper, thyme and oregano.
Transfer vegetables to a separate bowl.
Melt butter in the Dutch oven and stir in flour to create a roux. Whisk continuously to remove lumps and cook for 2 minutes to cook flour.
Once smooth, whisk in vegetable broth and heavy cream and cook for 5-10 minutes, or until mixture thickens.
Season with salt and pepper and ground mustard seed.
Return vegetables to Dutch oven and stir to make sure everything is evenly coated.
Take thawed puff pastry sheet, unfold it and gently press it into a large baking dish, making sure it comes up at least a little on all sides.
Pour vegetables into puff pastry crust, place baking dish in oven and cook for 20 minutes, or until set and bubbly.
Remove from oven and let cool 5 minutes before serving.