Preheat the oven to 175°C (340°F). Line a baking tray with baking paper. To make the frangipane, use a wooden spoon to beat the almond meal, butter and sugar in a bowl until well mixed. Add the egg, vanilla, almond extract (if using) and salt, then use a whisk to beat until light and creamy. Or, you can blitz all the ingredients together in a food processor or small blender.
Cut the hot cross buns along the cross. Spoon some frangipane into the centre and allow it to squish out over the top. Spread more frangipane on the tops. Spread the flaked almonds on a deep plate or bowl, turn the hot cross buns upside-down and press the frangipane into the flaked almonds.
Place the hot cross buns on the tray, right side up. Bake for 20 minutes, or until the tops are golden and bubbling. Some of the topping mixture will slip off and become crunchy, caramelised bits around the base — just quietly, these are the best bits, so treat them as chef’s snacks once cooled enough to scoff.
While the hot cross buns are still hot, combine the apricot jam and hot water and brush over to glaze.
Serve warm, or at room temp.