Heat oil in a pan and sauté the onions for 2-3 minutes until soft.
Add the chicken mince (or finely diced chicken), garlic paste, tomato purée and all the seasonings. Cook on medium-high heat for 9-10 minutes, breaking down the mince with a spatula.
Mix the cornflour with water to create a slurry, then pour it into the pan. Allow to simmer for 2-3 minutes until slightly thickened.
For the spinach: Either blanch it, squeeze out excess water and then add it to the chicken. Or add it directly into the pan, cover with a lid for 2 minutes to steam, then cook on high heat for 5 minutesuntil most of the water evaporates.
Stir in the double cream (or substitute with cream cheese or crème fraîche for creaminess), then remove from heat.
Allow the filling to cool completely in a bowl, then mix in the shredded mozzarella.
Cut the puff pastry into squares or rectangles—use ready-cut squares if preferred. Place a few tablespoons of filling in the center of each, ensuring not to overfill.
Seal the edges with a fork and make small slits on top to allow steam to escape (to prevent soggy pastry). Brush with egg wash or milk.
Bake in a preheated oven at 180°C for 20-25 minutes until golden brown.
