Preheat the oven to 180ºC/350ºF/Gas 4. Grease a 32 x 23cm/13 x 9in Swiss roll tin with oil and line it with baking parchment, leaving long edges of parchment over the sides.
To make the base, place the oats in a food processor with the ground almonds, flour, baking powder and xanthum gum and mix together.
Melt the butter in a small saucepan and add to the food processor with the flaked almonds and garlic. Add the beaten eggs and mix well to form a sticky dough.
Tip the mixture onto the prepared baking sheet and press down firmly, using your hands to form a thin crust.
Bake for 10 minutes until just lightly coloured.
Spread the Passata over the base of the tart. Top with the vegetables and cheese. Season with black pepper
Bake for 10-15 minutes until the cheese is bubbling. Leave to cool slightly, then cut into slices.
100g / 3 1/2oz Nairn’s Gluten Free Oats
100g /3 1/2oz ground almonds
50g / 1 3/4oz rice flour
1tsp baking powder
1tsp xanthum gum (optional)
125g/4 ½ oz butter
100g/3½oz flaked almonds
2 garlic cloves, minced
2 free range eggs, beaten
200ml / 7floz Passata (sieved tomato sauce)
6 cherry tomatoes halved
1 small red onion, finely sliced
2 roasted red peppers from a jar, drained and chopped
50g / 1 ¾ oz pitted black olives, halved
150g/ 5oz ball buffalo mozzarella cheese, torn into pieces
60g / 2 oz Cheddar cheese, grated
Freshly ground black pepper