Preheat the oven to 180°C. Line a 20-cm square cake tin with baking paper and grease well with nonstick spray. Keep a sheet of baking paper and baking beans, dry beans or rice handy.
1 Crust Mix the flour, sugar and salt in a mixing bowl. With the tips of your fingers, rub the butter into the mixture.
2 Make a well in the middle, pour the amasi into it and knead lightly until the pastry comes together. Shape into a ball and cover with clingfilm. Let the pastry rest in the fridge for 15 minutes.