Mushroom Empanadas with Chimichurri

Name: Mushroom Empanadas with Chimichurri
Ingredients: 500 g button mushrooms, halved and whole; 50 ml extra virgin olive oil; 200 g shallots, thinly sliced; 50 g unsalted butter; 2 garlic cloves, finely chopped; 1 tsp chilli powder; 2 tsp cinnamon; 1 tbsp cumin; 100 g sultanas; 50 g grated mozzarella cheese; 2 tbsp chopped spring onions, dark green parts only; Zest of 1 lemon; 6–8 frozen butter puff pastry sheets; 1 egg yolk; 1 tbsp water; Homemade or store bought chimichurri or dipping sauce of choice