Unroll the store-bought pie dough on a lightly floured surface and use a pastry cutter or glass to cut out circles slightly larger than your muffin cups. Press each circle into the muffin tin, easing into the corners. Chill the lined tin in the fridge for 10 minutes to help prevent shrinking.
Preheat your oven to 190°C (375°F). While it heats, sauté diced bell peppers and chopped spinach in a little oil until just tender and moisture has evaporated. Let them cool slightly before filling.
In a mixing bowl, whisk together the eggs, cream or milk, chopped thyme, salt, and pepper until smooth and slightly frothy. This creates a silky custard base for the quiches.
Add the shredded cheese, sautéed vegetables, and diced ham into the egg mixture. Gently fold everything together to distribute fillings evenly.
Spoon 1-2 tablespoons of the filling mixture into each pastry-lined muffin cup, filling about 2/3 full to leave room for puffing.
Pour the custard mixture over the fillings in each cup until nearly full, ensuring the ingredients are submerged and the filling is level.
Bake in the preheated oven for 20-25 minutes, or until the edges are golden brown and the filling is puffed and set in the center. The tops may crack slightly, which is normal.
Remove the mini quiches from the oven and let them cool in the tin for about 5 minutes. This helps the filling set further and makes them easier to handle.
Gently lift each quiche out of the muffin tin with a small spatula and transfer to a wire rack to cool slightly before serving.
Serve the mini quiches warm or at room temperature, garnished with extra thyme or herbs if desired. Enjoy their tender, custardy interior with a crisp, flaky crust.
