Preheat your oven to 350°F. While it heats, prepare your mise en place: slice tomatoes into 1/4-inch rounds and pat them thoroughly dry with paper towels—this prevents excess moisture from making the quiche watery. Mince the garlic cloves finely, tear the fresh basil into bite-sized pieces, and tear or cut the 6 ounces of mozzarella into small pieces. Have all ingredients measured and ready before you begin cooking.

Lightly oil or butter a 9-inch pie dish or similar baking dish. Layer the prepared tomato slices on the bottom, then scatter the minced garlic, torn basil, and mozzarella pieces evenly over the tomatoes. Sprinkle the crushed red pepper flakes across the filling—this adds a subtle heat that complements the fresh caprese flavors beautifully. The layering approach ensures each bite gets a balanced mix of ingredients.

In a mixing bowl, whisk together the 8 room-temperature eggs and milk until well combined and slightly frothy—room temperature eggs blend more smoothly and cook more evenly. Add the salt and pepper, whisking until fully incorporated. Carefully pour this egg mixture over the tomato and cheese filling in the baking dish, letting it flow into all the spaces. The egg custard will set around the filling and create a tender, savory crumb.

Bake the quiche uncovered at 350°F for 30-35 minutes, until the edges are set but the center still has a slight jiggle when you gently shake the pan—this indicates the custard is almost cooked through but still creamy. Remove from the oven and distribute the remaining 2 ounces of mozzarella over the top, then sprinkle the grated Parmesan cheese evenly across the surface. I like to add the cheese in two stages so the first layer melts into the custard while the top layer gets slightly browned and textured.

Return the quiche to the oven and bake for another 12-15 minutes, until the cheese on top is melted and lightly golden and the center is just barely set. Remove from the oven and let the quiche rest for 5 minutes before serving—this brief rest allows the custard to set slightly and makes it easier to slice cleanly. The residual heat will finish cooking the very center without making it rubbery.

Slice the quiche into wedges and serve warm or at room temperature. Garnish each slice with a few fresh basil leaves for a bright finish and an extra pop of fresh flavor that ties back to the classic caprese theme.