1Preheat oven to 350 degrees F (175 degrees C). Grease two 12 cup muffin pans and line with paper baking cups.
2Beat butter and sugar in a large bowl using an electric mixer until light and fluffy, about 15 minutes. Mix in the eggs one at a time, mixing each until well blended. Stir in the lemon extract. Stir in the flour, alternating with the lemon-lime soda, just until the batter is smooth. Spoon the batter into the prepared cups, dividing evenly.
3Bake in the preheated oven until the tops spring back when lightly pressed, 20 to 25 minutes. Cool in the pan set over a wire rack. When cool, arrange the cupcakes on a serving platter.