Preheat the oven to 325°F. Spray a 9x5-inch loaf pan with nonstick spray and line with a strip of parchment paper that covers the bottom and comes up over both sides of the short ends. The parchment paper should make little "handles" to help you remove the loaf from the pan later.
In a large bowl, cream the sugar and butter, either with an electric hand mixer or by hand (I HIGHLY recommend a hand mixer for this) until they are light and fluffy.
One at a time, add in the eggs, mixing well and scraping the sides as you go to get everything incorporated.
In a small bowl, mix together the Greek-style yogurt, lemon zest, lemon juice, and vanilla until well blended.
In another, medium-sized bowl, you're going to whisk together the dry ingredients: flour, baking powder, and salt.
Now the important part: Alternating between the wet (yogurt lemon mixture) and dry ingredients add them to the butter/sugar/egg batter. Start with the dry ingredients and add about ⅓ at a time. Mix after each addition until *just* combined. Be careful not to over-mix.
Pour the finished batter into the loaf pan and use a spatula to level the top. Bake for 60-70 minutes, or until a toothpick inserted into the center comes out clean. Place on a rack to cool. Cool for 15 minutes in the pan, then, using the parchment paper "handles", remove the cake from to finish cooling on the rack.
To Make the Blackberry Glaze:
Sift the powdered sugar into a medium sized mixing bowl. Be sure to remove any lumps. Add the lemon juice, water, and blackberry jam. Whisk until very smooth.
Pour the glaze over the top of the cake, spreading so that it runs down the sides. The glaze should be set after about 30 minutes.
Slice and serve it up!
Lemon Loaf Cake with Blackberry Glaze https://www.hungryhappyhome.com/lemon-loaf-blackberry/