Fit the pie crust into a 9-inch pie dish and gently press it into place.

Place the crust in the refrigerator while preparing the filling.

Wash and dry the zucchini and yellow squash thoroughly.

Use a vegetable peeler to create long, thin ribbons from both squashes.

Pat the ribbons dry with paper towels to remove excess moisture.

In a large bowl, whisk together the eggs, milk, heavy cream, garlic powder, Italian seasoning, salt, and pepper until smooth.

Stir in the Gruyère cheese and chopped chives.

Pour the egg mixture into the prepared pie crust.

Starting from the center, coil a squash ribbon into a small spiral and place it in the middle of the filling.

Continue wrapping additional ribbons around the center spiral, alternating zucchini and yellow squash for a decorative pattern.

Gently tuck the ribbons into the custard while keeping the spiral shape visible.

Brush the exposed squash ribbons lightly with olive oil.

Sprinkle the Parmesan cheese evenly over the top.

Place the pie dish on a baking sheet to catch any drips.

Bake until the center is set and the top is lightly golden, about 45 to 50 minutes.

Check that a knife inserted near the center comes out mostly clean.

Allow the quiche to cool for at least 15 minutes before slicing.

Serve warm or at room temperature for the best texture.