In a small bowl, combine the warm milk and active dry yeast. Let it sit for 5-10 minutes until frothy to ensure the yeast is active.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, ground cardamom, and salt. Make a well in the center and pour in the yeast mixture and the egg.

Mix until a shaggy dough forms, then add the softened butter. Knead for 8-10 minutes until the dough is smooth, elastic, and slightly tacky. Cover the bowl and let the dough rise in a warm place for 1 hour, or until doubled in size.

Punch down the dough and divide it into 12 equal pieces. Roll each piece into a smooth ball and place them into a greased jumbo muffin tin to force them to bake upward, creating a tall shape. Let them rise for another 30 minutes.

Preheat your oven to 375°F (190°C). Using the back of a spoon or your thumb, press a deep indentation into the center of each risen bun. Fill each hole generously with about a tablespoon of vanilla custard.

Bake the buns for 12-15 minutes until the dough is golden brown and the custard is set. Remove from the oven and let them cool completely on a wire rack.

In a small bowl, whisk the powdered sugar and water to create a thick icing. Spread the icing over the baked dough around the custard center, then immediately dip the iced portion into the shredded coconut. Serve with a hot cup of coffee or tea.