In a large bowl, combine the flour, cold butter, and a pinch of salt. With a pastry cutter or your fingertips, rub the butter into the flour until the mix resembles coarse crumbs.

Gradually add ice-cold water, mixing until a dough forms. Shape the dough into a disc, wrap it in plastic, and chill it in the refrigerator for at least 15 minutes.

After chilling, roll the dough out on a floured surface to about 1/4-inch thickness.

Carefully lift it into a 9-inch tart pan, pressing it into the edges. Trim any excess dough hanging over the sides.

Prick the base with a fork, then line it with parchment paper and fill with weights (like pie weights or dried beans). Bake in a preheated oven at 375°F (190°C) for about 12–15 minutes, then remove the weights and bake for another 5 minutes until lightly golden. Let it cool completely before adding the filling.

In a skillet, heat a drizzle of olive oil over medium heat. Sauté the roughly chopped spinach until wilted, which should take about 2-3 minutes.

Once cooked, drain and chop the spinach further to ensure it integrates smoothly into the filling.

In a mixing bowl, whisk together ricotta cheese, eggs, whole milk, grated Parmesan, nutmeg, black pepper, and sea salt until smooth.

Fold the sautéed spinach into the ricotta mixture, ensuring it’s evenly distributed.

Pour this filling into the pre-baked crust, smoothing it out with a spatula.

Return the quiche to the oven and bake at 375°F (190°C) for 25–30 minutes until the custard is set and slightly golden on top.

Once baked, let your quiche rest for about 10 minutes before slicing.

Garnish with finely sliced chives if desired. Serve warm or at room temperature.