Step 1: Preheat oven to 350°.
Step 2: Spray an 8-½-inch loaf pan with non-stick baking spray or butter and flour. Set aside.
Step 3: Whisk together the flour, baking powder, and salt in a small bowl.
Step 4: Put the sugar in a large bowl, add the lemon zest, and rub the zest into the sugar to release the lemon oil.
Step 5: Whisk the eggs into the sugar vigorously, one at a time.
Step 6: Whisk in the lemon juice, vanilla, then the heavy cream until smooth.
Step 7: Using the whisk, mix in the flour mixture in 3 additions.
Step 8: Add half the butter, mix with the whisk, then whisk in the rest of the butter.
Step 9: Stir in the poppy seeds with a silicone spatula, then scrape the batter into the prepared pan.
Step 10: Bake for 60-70 minutes or until the loaf rises, cracks across the top and a toothpick inserted in the middle comes out clean.
Step 11: Cool on a rack for 5 minutes, then carefully remove to a cooling rack to finish cooling.
