Veggie Bake with a Nutty, Oat Crumble

2 leeks chopped into slices
2 tbsp olive oil
4 cloves garlic sliced
1 large carrot chopped finely
1 sweet potato peeled and chopped into small cubes
125 mixed mushrooms finely chopped
6 tomatoes chopped roughly
250ml veg stock
1 tbsp tomato purée
1 tsp balsamic vinegar
1 tbsp smoked paprika
1/2 tsp sea salt
Black pepper
1 tbsp fresh thyme leaves
Pinch chilli flakes – optional

For the crumble topping
100g Mornflake Creamy Superfast Oats
3 tbsp chickpea flour
100g hazelnuts blitzed in a mini chopper or crushed
2 tbsp sesame seeds
1 tsp garlic powder
3 tbsp nutritional yeast
sea salt and ground black pepper, to taste
4 tbsp extra virgin olive oil