Pre-heat oven to 400 degrees.

Line a shallow 8.5 x 11.5 baking pan with parchment paper.

Roll out the pastry sheet and place in the parchment lines baking pan, folding over the sides. Poke holes in the crust with a fork and brush with olive oil. Bake 10 to 12 minutes or until crust starts to brown. Remove from oven and reduce heat to 350.

While crust is baking, saute onions until translucent, about one minute. Add the mushrooms, garlic and thyme to the pan and continue to saute 2 to 3 minutes. Season to taste with salt and pepper.

Remove pan from heat and toss the green beans with the mushrooms.

Spread 3 tablespoons of cheese over the crust.

Arrange mushrooms and green beans over the cheese, be sure to drain any liquid from mushroom mixture.

Sprinkle the remaining cheese over the top of the mushrooms and green beans.

Place in oven and heat until cheese starts to melt. When cheese has melted, remove from oven and sprinkle 2 teaspoons of thyme leaves over the tart.

Allow to cool slightly, slice and serve with a salad.