Preheat oven to 350 degrees, place rack at center level.

Stir together dry ingredients (flour, baking powder, salt, zest). Set aside.

Cut up your butter into smaller chunks and use one to grease your chosen pan. Beat butter and sugar together until well combined and light in color. If your butter is too cold to start, you might have to mix it extra, don't worry if it stays grainy.

Add eggs, one at a time, to the sugar and butter mixture. Then add vanilla, lemon juice, and milk one by one.

If you've been using an electric mixer, stop and start working with a spatula or spoon by hand. Add about a third of the dry ingredients and fold in gently, repeat until it is all just barely combined (you shouldn't see any large clumps of dry ingredients). Don't overwork your batter once the flour has been added, it will make the cake tough and chewy.

Spoon some batter into the corners of your loaf pan (or around the bottom edges of a circular pan). Gently fold in most of the blueberries to the remaining batter and pour into your pan, until it is 2/3 to 3/4 full. Lay the remaining blueberries on top of the batter. If you have remaining batter, pour into little ramekins or muffin tins, which you don't need to grease if you're planning on eating right out of those containers.

Bake for 40 minutes if using a 8x4 inch loaf pan, adjust time depending on the size of your pan. You can always test by poking with a toothpick to see whether the center bottom is still runny and liquid. Keep baking until a toothpick comes out with only a few crumbs or completely clean. It's normal for the top to turn a golden brown in places.

While the cake is baking, stir together the sugar and lemon juice for the soaking glaze.

Remove cake from oven and let cool for 15 minutes, then pour the soaking glaze evenly over the top. It should sink in immediately, if not, poke holes into the cake with toothpick and pour glaze again.

You could eat while it's warm or let cool in the refrigerator overnight for chilly sweet treat on a hot day.