Mix the butter with 1 cup of the sugar on medium high-speed for 1 minute. Beat in the eggs, one at a time, blending well after each, until the mixture is fluffy and pale yellow, about 3 minutes. Stir in the lemon rind.
In a medium bowl, whisk together the flour, baking powder & salt to combine. Fold the flour into the butter mixture using a spatula, mixing well. Gently knead the dough in the bowl for about 5 minutes.
Place the remaining 1/2 cup sugar in a shallow dish. Using a small cookie scoop, shape pieces of dough into balls, then roll in the sugar. Place the cookes on a parchment lined or lightly greased cookie sheet, 2 inches apart. Flatten the cookies gently using the tines of a fork or make the horizontal lines.
Bake for 18 - 20 minutes, or until a light golden colour. I like to rotate the cookie trays from top to bottom, halfway through the cooking process.
Cool on the cookie trays for about 10 minutes, then transfer to a cooling rack. Enjoy.