Preheat your oven to 356F/180C. Grease a 1-liter loaf tin with a little butter or line it with parchment paper for easy removal later.
In a small saucepan, bring the water to a boil. Add the Earl Grey tea bags into the boiling water and let them steep for about half an hour. This process extracts all the lovely flavors from the tea. Once done, remove the tea bags and squeeze out any excess liquid.
In a mixing bowl, sift together the flour, baking powder, and a generous pinch of sea salt. This helps aerate the flour, ensuring a light cake.
In the bowl of a stand mixer, combine the lemon zest, brown sugar, caster sugar, and butter. Beat these ingredients together until the mixture is light and fluffy, which should take about three to five minutes.
Add the eggs to the bowl one at a time, ensuring each one is fully incorporated before adding the next. This helps create a smooth batter and retains the airiness of the mixture.
Next, pour in the lemon juice, the infused Earl Grey tea, honey, and olive oil. Mix until everything is well blended, occasionally scraping down the sides of the bowl to ensure all ingredients are combined.
Stop the mixer and gently fold in the dry flour mixture. Do this carefully, mixing just until the ingredients are combined. Over-mixing can lead to a tough cake, so be gentle!
Pour half of the batter into the prepared cake tin. Scatter some blueberries evenly over the batter, followed by the remaining cake mixture. This layering ensures some fruitiness throughout the cake.
Bake the cake for approximately 30 minutes or until it turns a lovely golden brown. A toothpick inserted into the center should come out clean. If the top browns too quickly, cover it loosely with aluminum foil to prevent burning.
Once baked, remove the cake from the oven and allow it to cool in the tin for about ten minutes before transferring it to a wire rack to cool completely.
While the cake cools, prepare the glaze. In a small saucepan, combine the fine granulated sugar, fresh lemon juice, and water. Heat gently until the sugar dissolves. If you prefer a thinner glaze, add a bit more lemon juice to achieve the desired consistency.
Once the cake has cooled, spread the glaze over the top and decorate with any leftover blueberries. Serve immediately, and store any leftovers in an air-tight container in the fridge for up to four days.