Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper to make cleanup a breeze. If you're using frozen puff pastry, let it thaw according to the package instructions.
Once thawed, roll out your puff pastry on a floured surface. You can make individual tarts or go for a larger family-style tart, depending on your preference.
Brush the edges with egg wash
For the best texture, pre-bake your puff pastry for 10–12 minutes, or until golden and slightly puffed. This helps create a crispy base that won’t get soggy when you add the toppings.
While your pastry is baking, bring a pot of water to a boil. Add asparagus and blanch until just tender but still vibrant in color.
Mix whipped cream cheese, shallots, lemon zest, and Gruyère cheese.
Once your puff pastry is pre-baked and your asparagus is blanched, spread a thin layer of cheese mixture over the pastry.
Put the tart back into the oven for another 10–15 minutes, or until the cheese is melted and bubbly, and the pastry edges are golden brown and crispy. Top with the asparagus, and finish with a sprinkle of fresh chives.