Preheat oven to 350°F. Lightly grease a 9x5-inch loaf pan.
Using a hand or stand mixer, beat the butter and 1 cup of the sugar together on medium-high speed until smooth and fluffy, about 2 minutes.
1 cup unsalted butter, 1 cups granulated sugar
Add the eggs, one at a time, allowing them to fully incorporate before adding the next one. Then, add the vanilla extract and mix to combine.
4 large eggs, 1 teaspoon pure vanilla extract
With the mixer on low, gradually add in the flour--don't overmix!
2 cups all-purpose flour
Gently fold the blueberries and lemon zest into the batter.
1 cup blueberries, 2 teaspoons lemon zest
Transfer the batter to the greased loaf pan and top it with the remaining 2 tablespoons (0.12 cups) of sugar.
0.12 cups granulated sugar
Bake on the middle rack for 55-60 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 5 minutes. Then, run a knife around the edge and turn it out onto a wire rack to cool completely.