Preheat your oven to 180°C (350°F) and lightly grease your mini muffin tin with butter or non-stick spray.
In a mixing bowl, whisk together the eggs, heavy cream, salt, and pepper until the mixture is smooth and slightly frothy.
Stir in the grated cheese and chopped spinach, folding gently until evenly combined.
Pour the mixture into each muffin cup, filling about two-thirds full, ensuring an even distribution.
Bake in the preheated oven for 15-20 minutes, or until the quiches are puffed and golden around the edges with a slightly firm center.
Remove the mini quiche bites from the oven and let them cool slightly in the tin for a few minutes.
Transfer the bites to a wire rack to cool completely, or serve warm for best flavor and texture.
Enjoy these savory, portable bites on their own or with a side salad for a satisfying meal.