Step 1: Prepare Your Pan and Preheat
Preheat your oven to 325°F (165°C). This lower temperature ensures even baking without over-browning the edges. Line a 9×5-inch loaf pan with parchment paper, leaving overhang on the sides for easy removal. Lightly grease the parchment with butter or cooking spray. Set aside.

Step 2: Cream Butter and Sugar
In a large mixing bowl, beat the softened butter with an electric mixer on medium speed for about 1 minute until smooth and creamy. Gradually add the granulated sugar and continue beating for 4-5 minutes until the mixture is light, fluffy, and pale in color. This creaming process is crucial – it incorporates air that helps create the cake’s texture. Scrape down the sides of the bowl as needed.

Step 3: Add Eggs
Add the eggs one at a time, beating well after each addition (about 30 seconds per egg). The mixture should look smooth and glossy. If it looks slightly curdled, don’t worry – it will come together when you add the flour. Mix in the vanilla extract, lemon zest, and lemon juice until just combined.

Step 4: Combine Dry Ingredients
In a separate medium bowl, whisk together the flour, baking powder, and salt. This ensures even distribution of the leavening and prevents clumps.

Step 5: Alternate Adding Dry and Wet
With your mixer on low speed, add the flour mixture to the butter mixture in three additions, alternating with the sour cream in two additions. Start and end with the flour mixture. The pattern should be: flour, sour cream, flour, sour cream, flour. Mix each addition just until combined – don’t overmix! Overmixing develops gluten and can make your cake tough. Use a rubber spatula to fold the batter a few times to ensure everything is incorporated, scraping the bottom of the bowl.

Step 6: Pour and Smooth
Pour the thick batter into your prepared loaf pan. Use your spatula to smooth the top evenly. Gently tap the pan on the counter 2-3 times to release any air bubbles.

Step 7: Bake
Bake for 55-65 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs (not wet batter). The top should be golden brown and spring back when lightly pressed. If the top is browning too quickly after 40 minutes, tent loosely with aluminum foil.

Step 8: Cool Properly
Remove from oven and let the cake cool in the pan for 15 minutes on a wire rack. This brief resting period helps the cake set and makes it easier to remove. After 15 minutes, use the parchment overhang to lift the cake out of the pan and place it on the wire rack. Let cool for at least 30 minutes before glazing.

Step 9: Make the Glaze
In a small bowl, whisk together the powdered sugar and lemon juice until smooth. Start with 3 tablespoons of juice and add more for a thinner consistency. The glaze should be pourable but not too runny. Add lemon zest if desired for extra flavor and visual appeal.

Step 10: Glaze and Serve
Place the cooling rack over a baking sheet to catch drips. Pour the glaze over the slightly warm cake, letting it drip down the sides naturally. You can use a pastry brush to spread it evenly if needed. Let the glaze set for about 15 minutes before slicing. Cut with a sharp serrated knife, wiping the blade between slices for clean cuts.