Crack the eggs into a large mixing bowl and whisk them thoroughly until the yolks and whites are completely blended. Take a little extra time here to whisk well, as this helps introduce air into the mixture, resulting in a lighter, more tender quiche rather than a dense, omelet-like texture.

Add the ricotta cheese to the whisked eggs and mix gently until the mixture is mostly smooth. It’s perfectly fine if there are small pockets of ricotta remaining — these melt into the quiche as it bakes and add soft, creamy bites throughout the finished dish.

Fold in the cooked, well-drained spinach along with the salt, pepper, and any additional seasonings you’re using. Use a spatula and slow, deliberate folding motions to distribute the spinach evenly without breaking it down too much. This ensures the quiche has balanced flavor and texture in every slice.

Stir in the shredded cheese just until it is evenly incorporated. Avoid overmixing at this stage, as too much stirring can make the quiche dense and cause the cheese to sink unevenly during baking.

Pour the egg mixture into a lightly greased baking dish or pie dish. Use a spatula to smooth the top and gently spread the mixture into the edges so it bakes evenly. Lightly tap the dish on the counter once or twice to release any trapped air bubbles.

Place the dish into the preheated oven and bake until the center is fully set and no longer jiggly when gently shaken. The top should appear lightly golden, and the edges should pull away slightly from the sides of the dish, indicating that the quiche is cooked through but still creamy inside.

Remove the quiche from the oven and allow it to rest for several minutes before slicing. This brief resting time helps the custard finish setting, making the quiche easier to cut and allowing the flavors to settle before serving.