Heat oven to 180C/160C fan/gas 4. If you’re using bacon, put it into a large frying pan and cook over a gentle-medium heat. Stir occasionally until golden and beginning to crisp up.
Line a roasting tin, about 20 x 28cm, with baking parchment – just scrunch it roughly at the corners. Whisk together the eggs and milk in a large jug or bowl, then stir in the bacon or ham, plus any fat from the pan, the cheddar and some seasoning.
Pour into the tin, scatter with a bit of extra grated cheese, if you like, and bake for 30-35 mins until golden and set. Carry to your picnic in its tin and eat hot, warm or cold, with gluten free bread, tomatoes and a few salad leaves.