Heat your oven to 220°C (450°F) and grease a 9x13 inch baking dish or similar size. While the oven preheats, soak the raisins in warm water for 10 minutes to plump them up and make them extra juicy—this step makes a real difference in the final texture. Cube the cold butter into 1/2-inch pieces and set aside. This prep work ensures everything is ready when you start building the dough.

In a large mixing bowl, combine the self-raising flour, salt, mixed spice, cinnamon, and ground nutmeg. Whisk these together thoroughly to distribute the spices evenly—this ensures consistent flavor throughout all eight buns. The combination of warm spices is what gives hot cross buns their distinctive taste, so don't skip this step.

Add the cubed cold butter to the dry ingredient mixture and rub it in with your fingertips until the mixture resembles coarse breadcrumbs. This technique creates small pockets of butter throughout the dough, which will produce a tender, slightly flaky crumb in the baked buns. Work quickly to keep the butter cold—this makes all the difference in achieving the right texture.

Drain the soaked raisins and stir them into the mixture along with the sugar. In a small bowl, whisk together the egg and milk, then pour this into the flour mixture while stirring gently with a fork until a soft, slightly sticky dough forms. You may not need all the milk—add it gradually until you reach the right consistency. The dough should come together but still be moist enough to handle. I prefer a dough that's slightly wetter rather than dry, as it leads to moister buns.

Turn the dough out onto a lightly floured surface and gently roll it to about 1cm thickness. Using a round cutter or cup about 3 inches in diameter, cut out 8 circles. Place these circles into your prepared baking dish, leaving a little space between each one for them to rise slightly during baking. Don't worry if they're touching—they'll stay separate enough.

In a small bowl, mix together the 1/2 cup flour and 1/3 cup water, stirring gradually until you achieve a thick, pipeable consistency—it should look like thick cake batter. Transfer this paste to a piping bag fitted with a small round tip (or use a sandwich bag with the corner snipped off). Pipe a cross on top of each bun, making two intersecting lines from edge to edge. This is what makes them 'hot cross buns,' so take a moment to make them look nice.

Bake the buns for 15-20 minutes until they're golden brown and a toothpick inserted into one comes out clean. While they bake, prepare the glaze by mixing together the 1 1/2 tbsp sugar, gelatin, and 1 tbsp hot water in a small bowl, stirring until the sugar and gelatin dissolve completely. Once the buns come out of the oven, brush the warm glaze generously over each bun—it will set as it cools, creating a subtle sweet finish. For an extra glossy, caramelized finish, you can optionally place the buns under the broiler for 1-2 minutes, but watch them carefully to avoid burning.