Preheat the oven to 350°F. Grease a 9x5 inch loaf pan and line with parchment paper. Set aside.
In a medium bowl, whisk together the flour, baking powder, and salt.
In a large bowl, add the sugar and softened butter. Using a hand-held mixer, cream the butter and sugar until light and fluffy, about 2 minutes. Add the sourdough discard, eggs, lemon zest, lemon juice, yogurt, and vanilla extract. Mix until smooth and combined.
Add the dry ingredients to the wet ingredients and mix until just combined. Using a spatula or wooden spoon, fold in the raspberries.
Pour the batter into the prepared pan and bake for 60-70 minutes or until the top is golden and a toothpick inserted into the center of the loaf comes out clean. Remove from the oven and let cool for 10 minutes in the pan. Then remove the loaf from the pan (you can pick up the loaf from the edges of the parchment paper) and transfer to a wire rack to cool fully.
Once the loaf has cooled, combine the powdered sugar, lemon juice and vanilla extract in a small bowl and whisk to combine. This will be a thick glaze. Pour over the cooled loaf, slice and enjoy!
Video
Notes
Using frozen raspberries: You can use fresh or frozen raspberries to make this loaf cake. If using frozen, do not thaw the berries before adding to the batter. Using other berries: This recipe is written using raspberries, but would also be delicious with blueberries or blackberries!