For the mushroom quiche filling: In a pan over medium heat, add a spoonful of olive oil. When it gets hot, add the mushrooms, onion, and garlic powder. Sauté the mushrooms until they become golden. Transfer them to a bowl and let them cool.
For the spinach quiche filling: In another pan over medium heat, add the butter, crushed garlic, spinach, and green onion. Sauté until the spinach is soft. Transfer to a bowl and let it cool.
Preheat the oven to 190°C.
Assemble: Using a glass or pastry molds, cut 24 circles from the sheets of soft dough. The circles should be 2-3 cm wider than the bottom of your muffin tin.
Lightly grease the muffin tin and place the dough circles at the bottom of each form to form the crust for the mini quiches.
In a blender, add the ingredients for the base. Mix briefly to obtain a liquid and well-incorporated composition.
Fill each formed crust with the appropriate filling. Use 6 circles for each type. Divide the batter equally among the crusts, then pour the liquid base over each quiche, making sure not to exceed the edges of the crust. Sprinkle a bit of grated Gouda over each mini quiche.
Place the muffin tin with mini quiches in the oven and bake until they turn golden and rise. Serve hot or cold. Enjoy!