• Preheat the oven to 425 °F (220 °C). Line two 6-cup muffin pans with 10 muffin paper liners being sure to space them out between the two pans to allow better air flow.

Make the muffin batter

• In a large bowl, combine the granulated sugar and lemon zest. Using your fingertips, rub the ingredients together. This will help bring out the oils in the zest, adding more flavour.
• Whisk in the flour, baking powder, baking soda, and salt.
• Add the cubes of softened butter and work it in with your hands, rubbing it in until the mixture resembles coarse sand.
• In a separate bowl, whisk together the sour cream, lemon juice, eggs, and vanilla.
• Add the wet ingredients to the flour mixture and stir it in (takes about 20 stirs to get the batter mixed).
• Fold the cranberries into the batter gently with a wooden spoon or spatula to evenly distribute them.
• Divide the batter between the 10 paper-lined wells of the two muffin pans.
• Bake at 425°F for 8 minutes, then drop the temperature to 350 ºF and continue baking until a cake tester inserted into the middle of a muffin comes out clean to check if the muffins are baked. This takes about 15 minutes more and the edges start to turn golden.
• Let cool slightly in the pan before transferring to a wire rack to cool completely.

Make the glaze

• Whisk together the ingredients of the glaze and drizzle the tops of the muffins with it. The glaze should be very thick so that it doesn't all run off. Make sure the muffins have cooled down fully before glazing or the heat will cause the glaze to run off.