Cheesy oats baked with the tang of apple, crunchy walnuts, and flavoured with celery seed.
Eat as a snack, in packed lunches or on picnics. Great hot or cold as a main course with a side of veg or salad too.
Preheat the oven to 180C / 160C Fan / Gas 4.
Butter a 20cm square baking tin or line it with baking paper.
In a large bowl, stir together all the ingredients except the butter.
Melt the butter in a small saucepan and pour it over the ingredients in the bowl. Stir well to combine.
Transfer the mixture to the baking tin, spreading it evenly across the base, making sure to go right into the corners. Smooth down the top.
Bake in the oven until cooked through, slightly risen and golden brown (approx 35 min).
Remove from the oven and cut into 9 pieces while still hot, but leave in the tin to cool.
When barely warm, or completely cold, remove the flapjacks from the tin.
Store in an airtight container once cold.
Should keep for 3-4 days in the fridge or can be frozen.
Eat cold or reheat in a microwave or low oven.