Step 1
Heat milk in a small saucepan to 110 degrees F (43 degrees C); pour milk into a bowl. Whisk 1/2 cup flour and yeast into milk; cover with plastic wrap and let stand until bubbly about 15 minutes.
Step 2
Place 1 2/3 cups flour 1/3 cup white sugar salt cinnamon cloves ginger and nutmeg into the bowl of a stand mixer with paddle attachment; turn mixer on for a few seconds on low speed to combine. Place butter into flour mixture; mix on low speed until incorporated about 2 minutes.
Step 3
Place yeast mixture and egg into flour mixture; mix on low speed for 2 minutes. Stop mixer and allow to rest for 10 minutes; mix on medium speed until smooth and elastic about 2 minutes. At slowest speed mix currants and citron into dough until evenly distributed about 1 minute.
Step 4
Butter the inside of a large bowl; place dough in bowl turn to butter dough on all sides. Cover bowl with plastic wrap; let dough rise in a warm place until doubled in size about 1 hour.
Step 5
Line a baking sheet with parchment. Turn dough out onto a lightly floured surface. Pat dough into a rough square and cut into 12 equal pieces. Form each piece into a round bun; place on prepared baking sheet. Press a cross into each bun with the back of a knife; cover buns with a damp cloth and allow to rise until doubled in size about 45 minutes.
Step 6
Preheat oven to 375 degrees F (190 degrees C).
Step 7
Bake buns in the preheated oven until deep golden brown about 15 minutes.
Step 8
Bring 2 tablespoons white sugar with 1 tablespoon water to a boil in a small saucepan. Remove buns from oven; lift parchment and transfer buns to a wire rack. Brush immediately with sugar glaze; allow buns to cool completely about 20 minutes.
Step 9
Stir confectioners' sugar and remaining 2 teaspoons water together in a small bowl; heat icing mixture in microwave until smooth and warm to the touch about 10 seconds. Place icing in a sandwich bag snip off one corner of the bag and pipe in a cross over fully cooled buns; allow icing to dry for 30 minutes.