Preheat the oven to 350 degrees, and grease and line a loaf pan with parchment paper.
Whisk the flour, baking powder, baking soda, and salt in a medium bowl. Set aside.
Beat the sugar and eggs in a mixer for a full 2 minutes.
Add the butter and oil and mix again until combined.
Add the vanilla and lemon extracts, the lemon zest, and the lemon juice. Beat on medium speed until combined.
Mix in the sour cream.
Slowly mix the dry ingredients into the wet ingredients until just combined.
Pour the batter into the baking pan and bake for 45 to 50 minutes until a toothpick inserted into the center comes out clean.
Cool the cake completely in the pan before frosting.
Frosting
Whisk the powdered sugar, lemon juice, and heavy cream until combined.
Pour the frosting over the cooled cake.
Notes
Storage
Store the cake at room temperature for up to 3 days in an airtight container.
You can refrigerate the cake for up to 5 days in an airtight container.
For longer storage, wrap the loaf in a double layer of plastic wrap and a layer of foil and freeze for up to a month.
Wrap individual slices in plastic wrap and freeze them for up to a month in an airtight, freezer-safe container.
Bring the cake to room temperature before serving.
Tips
Always use fresh lemon juice whenever possible. Bottled lemon juice is more bitter and creates a cake with a puckery flavor rather than a bright flavor.
For faster cooling, remove the cake from the pan after about 10 minutes and transfer it to a wire rack.
We recommend sifting your powdered sugar before making the frosting to ensure a completely smooth frosting.