Prepare your short-crust pastry. Gently press it into an 11-inch / 28 cm quiche pan, trimming any excess. Pre-bake (blind bake) the crust according to your recipe's and set aside.
In a medium skillet, heat the olive oil over medium heat.
Add the sliced onion and garlic and sauté, stirring occasionally, until soft, sweet, and golden brown, about 10-15 minutes.
Spread the caramelized onion and garlic mixture evenly over the bottom of the pre-baked pastry shell, then sprinkle the grated Swiss cheese on top.
In a separate bowl, whisk together the eggs, heavy cream, a pinch of salt, and a few grinds of black pepper until smooth. Carefully pour this custard mixture over the cheese in the shell.
Artfully arrange the sliced pimiento peppers and olives over the top of the custard.
Preheat your oven to 450°F / 230°C.
Bake the quiche for 15 minutes at 450°F / 230°C.
Then, reduce the oven temperature to 350°F / 175°C and continue to bake for another 10 to 15 minutes. The quiche is done when the center is just set (it should have a slight wobble) and the top is lightly browned in spots.
Remove the quiche from the oven and let it cool on a wire rack for at least 15-20 minutes before slicing. This allows the custard to set fully.
Serve warm or at room temperature.
Don't skip blind baking the crust! This crucial step prevents a soggy bottom and ensures a crisp, flaky base for your delicious filling.
Patience is a virtue!
Letting the quiche rest for at least 15-20 minutes after baking is essential. It allows the custard to set completely, making for clean, beautiful slices.