Step 1Heat the oven to 375 degrees. Spray 3 (6-cup) nonstick muffin pans with nonstick cooking spray. Set aside.
Step 2Stir together the flour, baking powder and salt in a bowl. Set aside.
Step 3Cream together the butter and sugar. Beat in the egg substitute and vanilla.
Step 4Stir together the sour cream and baking soda.
Step 5Stir the flour mixture and sour cream mixture into the butter and sugar. Mix the ingredients just until they're blended. Do not overbeat.
Step 6Fill the muffin cups halfway with batter. Spoon about 1 teaspoon lemon curd into the center of each muffin cup then divide the remaining batter among the muffin cups, covering the lemon curd. Sprinkle each muffin with poppy seeds. Bake the muffins until a toothpick inserted in the middle comes out clean, 15 to 20 minutes.