Stuffed baby squash with creamy mushrooms tarragon

Name: Stuffed baby squash with creamy mushrooms & tarragon
Ingredients: 4 onion or acorn squash; 4 tbsp olive oil; 50g dried wild mushrooms; 2 banana shallots peeled and sliced; 200g chestnut mushrooms finely chopped; 2 garlic cloves crushed; 100ml vegetable stock; 250g cooked mixed grains; 4 tbsp crème fraîche; ½ small bunch of tarragon finely chopped; 80g mature cheddar finely grated