Preheat an oven to 400u02daF. Line a baking sheet with parchment paper.
Bring a pot of salted water to a boil over high heat. Add the potatoes and cook for about 3 to 5 minutes. Drain and season with salt and pepper.
Spread the cream cheese evenly over the pastry and top with the sliced potatoes and sliced zucchini. Sprinkle fresh thyme, parsley and asiago cheese on top.
Place the tart on the prepared baking sheet and bake until puffed, 10 to 13 minutes. Remove from the oven.
Garnish with fresh spinach. Cut into pieces and serve immediately.