Melt butter in a pan over medium heat. Add leeks and cook for 3 to 4 minutes, until tender. Remove from heat and let them cool.
In a bowl, whisk eggs with milk and seasonings.
Set the frozen tartlet crust over a baking sheet. Divide the leek and goat cheese inside the crust. Pour the egg and milk mixture over the crust, then spread the walnuts.
Oven bake for 25 to 30 minutes, until the center of each tartlet is well cooked.
Did you know that...
1 package of sliced leeks contains the equivalent of 2 whole leeks.