Proceed with Step 1 as directed. In Step 2, stir together sugar, yeast, salt, zest, cinnamon, cardamom, nutmeg, and 4 1/4 cups of the flour in a large bowl using a wooden spoon. Add milk, butter, and eggs; stir until a shaggy dough forms. Turn out onto a clean work surface, and knead until dough is smooth and elastic, 8 to 10 minutes. Dough will be very sticky and will smear across work surface for first few minutes until gluten is developed (use a bench scraper to bring dough back into a ball after smearing). Spread dough into a 9-inch circle; pile raisins and currants on top. Fold dough in half to sandwich add-ins; knead until evenly incorporated, 1 to 2 minutes. Continue with Steps 3 through 6 as directed.