1. Preheat the oven to 375°F.
2. Line a tart mold with the pie dough. Cover the dough with parchment paper and bake for 15 minutes. Remove from the oven.
3. In a saucepan, melt the butter. Add the leeks and cook for 5 minutes. Add the cream, nutmeg, and diced ham. Cover and simmer for 10 minutes over low heat.
4. In a small bowl, beat the eggs. Add to the leek-ham mixture; mix well.
5. Pour the mixture into the tart crust.
6. Return to the oven and cook for 20 minutes, or until the top of the flamiche is golden brown. Serve warm.