Savory Leek and Onion Cream Tart

Prepare the crust: In a mixing bowl, rub 6 teaspoons of the butter into the flour using your fingertips until the mixture resembles coarse crumbs.

In a separate bowl, whisk together the egg yolk, 1/2 teaspoon salt, and water. Add to the flour mixture and gently mix until a soft dough forms.

Let the dough rest at room temperature for 30 minutes. Roll it out thinly, line a tart pan, and refrigerate while you prepare the filling.

Preheat the oven to 375°F (190°C).

Melt the remaining 2 teaspoons of butter in a skillet over medium heat. Add the chopped onion, leek, and dried thyme. Sauté gently until soft and fragrant, without allowing them to brown. Remove from heat.

Spread the cooked onion and leek evenly over the chilled tart crust.

In a bowl, whisk together the eggs, cream, a pinch of salt, and black pepper. Pour the custard mixture evenly over the vegetables.

Sprinkle the grated mozzarella evenly across the top.

Bake for about 30 minutes, or until the filling is just set and the surface is lightly golden. Allow the tart to rest for a few minutes before slicing. Serve warm with fresh leafy greens.