Step 1: Preheat your oven to 350°F (175°C). Grease and flour a 9x5 inch loaf pan, or line it with parchment paper for easy removal.
Step 2: In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set the dry ingredients aside.
Step 3: In a large mixing bowl, whisk together the granulated sugar, large eggs, sour cream, canola oil, fresh lemon juice, lemon zest, and vanilla extract until the mixture is smooth and well combined.
Step 4: Gradually add the dry ingredients from Step 2 to the wet ingredients in the large bowl. Mix gently until just combined. Be careful not to overmix the batter, as this can lead to a tough loaf.
Step 5: In a separate small bowl, use an electric mixer to beat the softened cream cheese and powdered sugar together until the mixture is smooth and creamy. This will be your luscious cream cheese swirl.
Step 6: Pour about half of the lemon bread batter into the prepared loaf pan, spreading it evenly. Dollop spoonfuls of the cream cheese mixture over the batter.
Step 7: Carefully pour the remaining lemon bread batter over the cream cheese layer, covering it completely. Take a butter knife or a skewer and gently swirl through the batter a few times to create a beautiful marbled effect with the cream cheese.
Step 8: Bake in the preheated oven for 50-60 minutes, or until a wooden skewer or toothpick inserted into the center of the bread comes out clean. If the top starts to brown too quickly, you can loosely tent it with aluminum foil.
Step 9: Once baked, remove the loaf pan from the oven and let the bread cool in the pan for about 10-15 minutes. Then, carefully transfer it to a wire rack to cool completely before slicing and serving. This allows the cream cheese swirl to set properly.