Preheat the oven to 350 degrees. Cut a piece of parchment paper to the length of the bottom of the pan. Spray the pan with cooking spray, then lay in the parchment so it hangs over the edges on the long side. Spray again on top of the parchment.

In a large mixing bowl, beat together the sugar, oil, lemon zest, and juice until thoroughly combined. 

In a large glass measuring cup, beat together the buttermilk and eggs.

In a third bowl, whisk together the flour, salt, baking powder, and poppy seeds.

Add the dry ingredients to the sugar mixture in three additions, alternating with the buttermilk mixture, stirring gently and scraping the bowl as needed.

Toss the blueberries with the 2 Tablespoons of flour then gently fold them into the batter. Pour the batter into the prepared pan.

To make the crumbs, combine the flour, sugar, and melted butter in a bowl. Whisk or use your fingers to mix the ingredients together until fine crumbs form. Spread the crumbs on top of the batter.

Bake for 55-65 minutes or until a toothpick inserted in the center of the bread comes out clean. Remove the bread from the oven and place it on a rack to cool for at least 10 minutes. To release, run a knife around the short edges of the loaf pan and lift using the parchment overhang on the sides. Allow the cake to mostly cool before glazing.

To make the glaze, whisk together the powdered sugar, lemon juice, and milk until the consistency is smooth and pourable (add more milk if needed). Pour the glaze over the cake and serve.