2 Tbsp unsalted butter - plus extra for custard cups
2 slices bacon, chopped
3 cups sliced leeks, white and pale green parts only
1-1/2 cups half and half
3 large eggs
1/3 cup grated Parmigiano cheese
1/2 tsp salt
1/4 tsp white pepper
1/8 tsp ground nutmeg
Preheat oven to 350 F. Butter six 3/4 cup custard cups. Set aside.
Place bacon in a heavy large skillet and turn on heat to medium. Cook bacon for 7 minutes. Reduce heat to medium low and add butter and allow to melt. Add leeks and sweat until very tender and just starting to get some color, about 10 minutes. Let cool for 10 minutes. Transfer to a food processor or blender and puree until a coarse paste forms. Add half and half and blend well. Add eggs, cheese, salt, pepper, and nutmeg. Blend until well combined.
While leeks are cooking, put a large saucepan of water on to boil. Turn burner off and allow water to stop boiling before proceeding with next step.
Divide mixture evenly between the 6 cups. Place cups in a baking pan large enough to hold all of them. Place baking pan in oven with the rack partially out. Fill a measuring cup with the hot water and pour into baking pan. Repeat until water is about half-way up the cups. Gently and carefully push oven rack into place, trying to avoid water splashing into your custard cups. Bake until custards are set in the middle, about 40 minutes. Carefully remove from water and allow to cool for 15 minutes. Run a knife around the edges to loosen the custards, turn out onto plates and serve warm.
TIP: If you have canning jar holders/grippers, they work great to take the custard cups out of the hot water. Alternatively, use a wide spatula to slide under the bottom and tongs to steady the custard cups.