Blend on pulse setting until they look like breadcrumbs. Add the grated carrot and continue to pulse until the mixture comes together to form a ball. If you don’t have a blender or food processor you can just rub the butter into the dry ingredients, add the carrots and press together until a ball is formed.
Carefully the ball out into a disc of pastry and use it to line a shallow pie pan. Chill.
Saute the onions on low heat in oil for about 15-20 mins until beginning to caramelise. Place the beetroot in the pastry case and cover with the onions. Whisk the eggs and milk together, season and pour over the onions and beetroot. Bake for 15 mins at 180 then a further 45 mins at 160.
Serve with a rocket and pear salad.