Preheat the oven to 170ºC, fan 150ºC, gas 3. Lightly grease a 6-hole muffin tin.
Make the tartlet cases. In a large bowl, mix together all the ingredients for the cases until well combined, then press the mixture into the muffin tin. Use a spoon to ease the mixture up the sides of each muffin hole, forming ‘cases’.
Make the filling. Heat the oil in a small frying pan over a medium heat, add the onion and fry for 5 minutes until soft. Cool a little and divide between the tart cases.
In a jug, whisk together the eggs, egg yolk, crème fraîche and dill. Season with freshly ground black pepper, then pour into the prepared salmon cases.
Scatter over the cheese and bake for 20-25 minutes until set. Remove from the oven and leave for 5 minutes to firm up.
Run a knife around the edge of each tartlet, then use a spoon to carefully lift out of the tin.
Cook’s tip: these gluten-free tartlets are ideal for picnics, packed lunches or supper in the garden.