Prepare the Crust

1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease a 12-cup muffin tin or line it with cupcake liners for easy cleanup.
2. Roll Out the Pie Crust: If using refrigerated pie crusts, unroll them onto a flat surface. Use a round cutter (a glass works perfectly) to cut out circles slightly larger than your muffin tin cups.
3. Fit the Crusts into the Tin: Gently press each circle into the muffin tin to form little crusts. Make sure to push them into the edges so they hold their shape.

Make the Filling

1. Whisk the Eggs: In a large mixing bowl, whisk together the eggs and heavy cream until fully combined.
2. Add the Fillings: Stir in the shredded cheese, cooked bacon, spinach, onion, salt, and pepper. Mix everything together until the ingredients are evenly distributed.
3. Fill the Crusts: Spoon the filling mixture into each pie crust, filling each cup about three-quarters full.

Bake the Mini Quiches

1. Bake: Place the muffin tin in the preheated oven and bake for 25-30 minutes, or until the quiches are golden brown and the filling has set (a knife inserted should come out clean).
2. Cool: Let the mini quiches cool in the tin for 5 minutes before removing them. You can use a butter knife to gently lift them out.