Method

Preheat oven to 400 degrees F. Spray a mini muffin tin with cooking spray and set aside.
Cook the bacon in a skillet over a medium to high heat until crispy, or in the oven at 400 degrees for about 18 to 20 minutes. Transfer the bacon to a paper towel lined plate, reserving 1 tbsp of the bacon fat.
In the same skillet (or new one if you did oven baked bacon), add 1 tbsp of bacon fat over a medium heat. Add the leaks and cook, stirring occasionally, until softened, for about 5 to 7 minutes. Let cool.
In a large bowl, combine the cream, cheese, eggs, egg yolks, thyme, salt, pepper, and nutmeg. Add the cooled leeks and bacon and stir to combine.
To make the mini muffins, roll out one sheet of pastry onto a floured surface. Cut roughly 2″ squares of filo pastry and press into the mini muffin tins.
Fill each one right to the top of the dough. Bake in a preheated oven for about 20 to 25 minutes, until the filling is puffed and the crust is golden brown.