1. Heat oven to 180 degC. Brush a 17 x 27cm slice tin with oil. Cook cubed potatoes in boiling salted water for 5 minutes or until just tender. Drain well and then scatter over the base of the prepared tin.
2. In a bowl, whisk eggs with milk, cream and grated parmesan cheese. Season with salt to taste and cayenne pepper. Pour mixture into tin to cover potatoes.
3. Bake for 20 minutes or until set. Remove to cool in the tin. Turn out frittata and cut into 28 cubes. Cut salmon into 28 pieces.
4. Top each cube of frittata with a little sliced smoked salmon and a small dollop of sour cream.

Tip: The frittata can be made up to two days in advance and stored covered in the refrigerator. Slice and add topping just before serving