Step 1 Preheat oven to 200°C. Line a large baking tray with non-stick baking paper. Place sweet potato on tray, spray with olive oil and season with freshly ground black pepper. Bake for 20 minutes or until golden. Set aside.
Step 2 Meanwhile, heat a large non-stick frying pan over medium heat and spray with olive oil. Add leek and cook, stirring occasionally, for 5 minutes or until soft. Add garlic and cook, stirring, for 1 minute. Add ham and stir to combine. Remove from heat.
Step 3 Blanch broccoli in a saucepan of boiling water until bright green and tender crisp. Drain well.
Step 4 Line the base and sides of a 20cm round cake tin with a single piece of non-stick baking paper. Arrange sweet potato, leek mixture and broccoli over the base of the tin. Whisk together eggs, egg whites and milk in a bowl. Pour over the vegetables and top with slices of mozzarella.
Step 5 Bake for 25-30 minutes or until frittata is golden, puffed and set in the middle. Cut into wedges and serve with salad leaves.