Halve the leeks lengthwise and slice 1/4 of an inch thick. Rinse the leeks of any residue dirt. Set aside.
Heat 1 tablespoon of olive oil over medium-high heat in a large, well-seasoned cast-iron skillet or ovenproof nonstick skillet. Add the sliced leeks and saute for 4 - 6 minutes, or until the leeks are tender. Remove from heat. Add the ham and saute for an additional 1 - 2 minutes to allow the flavours to develop.
In a large bowl, whisk the eggs, milk, 1/2 teaspoon salt, and 1/8 teaspoon black pepper (or amounts according to your preferences).
Remove the leeks and ham from the skillet and add to the whisked eggs along with the crumbled goat cheese. Gently stir to combine.
Wipe out the skillet and grease the bottom and sides of the skillet with the remaining 1 tablespoon of olive oil. Set the skillet over medium-low heat. Slowly pour the egg mixture into the prepared pan. Cook over medium-low heat without stirring for 8 - 10 minutes, or until the bottom is set.
Transfer the frittata to the oven and bake until the top is set, about 5 - 10 minutes more. Cut into wedges and serve immediately.
Make Ahead Option
Cool the baked frittata completely, cut into individual portions and store in a sealed food safe container in the refrigerator for up to 3 days. Reheat portions as needed.