Preheat an oven to 375 F. In a mixing bowl, whisk the eggs, half and half, salt, and pepper until smooth. Set aside.
Heat a 10 inch nonstick skillet over medium low heat. Add the diced bacon to the skillet and cook, stirring occasionally, until the bacon is crispy and the fat is rendered. Using a slotted spoon, transfer the bacon to a plate. Remove all but 1 tablespoon of bacon fat.
Increase the heat to medium and add the leeks. Season with salt and pepper and cook for 4-5 minutes, until the leeks are tender. Once the leeks are tender, pour the whisked eggs into the skillet. Stir slightly to evenly distribute the leeks.
Sprinkle the top of the frittata with the crispy bacon and cheese. Transfer the skillet to the oven for 16-18 minutes, until the eggs are puffed and just barely jiggle. Remove from the oven and cool for 10 minutes in the skillet.
Transfer the frittata to a plate, sprinkle with minced chives, and cut into wedges. Serve immediately.