Mushroom & Chestnut Crumble - Deliciously Yorkshire

Ingredients

• A good drizzle of Yorkshire Rapeseed Oil
• 1 medium red onion, finely sliced
• 2 cloves garlic, finely chopped
• 1 leek around 150g, sliced
• 250g mushrooms, sliced
• 1 tsp dried mixed herbs
• 180g cooked chestnuts, whole
• 1½ tbsp plain flour
• 100ml white wine (or swap out with extra stock)
• 120ml hot vegetable stock
• Salt & pepper, to taste
• 4 slices seeded bread
• 2 sprigs fresh rosemary, leaves stripped off the stem
• A handful of walnuts
• Pinch of salt and a twist of black pepper
• 2 tbsp Yorkshire Rapeseed Oil (or try their Garlic or Smoked Oils)