Preheat your oven to 350°F (175°C). Grease and flour a standard 9x5 inch loaf pan, or line it with parchment paper.

In a small bowl, toss the chopped rhubarb with 2 tablespoons of granulated sugar. Set aside.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream together the softened butter and 1 cup of granulated sugar until light and fluffy (about 3 minutes). Beat in the eggs one at a time, ensuring each is fully incorporated. Stir in the lemon zest and 2 tablespoons of lemon juice.

Alternately add the dry ingredients and the milk to the wet ingredients, beginning and ending with the dry mixture. Mix until just combined; do not overmix.

Gently fold in the sugared rhubarb pieces. Pour the batter into the prepared loaf pan and spread evenly.

Bake for 50 to 55 minutes, or until a wooden skewer inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes before carefully turning it out onto a wire rack to cool completely.

While the cake cools, prepare the glaze: Whisk together the powdered sugar and 2 tablespoons of lemon juice until smooth and pourable. If the glaze is too thick, add a few drops more juice; if too thin, add a bit more powdered sugar.

Once the loaf is completely cool, drizzle the lemon glaze evenly over the top. Allow the glaze to set before slicing and serving.