Preheat the oven to 400 degrees. Heat the olive oil in a medium 10" cast iron or heatproof skillet over medium heat. Add the leek and cook 3 minutes until softened. Add the garlic and cook 30 seconds more. Add the baby spinach and cook 2-3 minutes or until completely wilted, then pour the mixture out onto a cutting board and roughly chop.

Brush olive oil from the bottom of the pan around the edges of the skillet (or add more oil if needed), then add the spinach mixture back to the pan and spread evenly across the bottom.

Beat the eggs with the half and half until well blended, then whisk in the feta cheese, chopped dill, salt and pepper to taste until combined. Pour the egg mixture over the top of the spinach mixture.

Cook the frittata on the stove top over medium heat just until the edges begin to set (about 2 minutes), then place in the oven. Bake for 8-10 minutes or until puffed and golden on top. Remove from heat and allow to cool slightly. Enjoy!