Preheat your oven to 175°C (350°F). Line a baking sheet with parchment paper. This prevents sticking and ensures even baking.

In a bowl, combine flour, baking soda, baking powder and salt. Whisk well to mix evenly. Set aside for later use in the dough.

In a large mixing bowl, beat butter and sugar with an electric mixer until fluffy. This takes about 2–3 minutes. The mixture should be light and smooth.

Add the egg and vanilla extract to the butter-sugar mixture. Beat until fully combined. This adds moisture and flavor to the cookies.

Gradually add the dry ingredients to the wet mixture. Mix on low speed until the dough comes together. Do not overmix to keep cookies soft.

Roll dough into small balls, about 1 inch in diameter. Roll each ball in extra sugar for a sparkling effect. Place them on the prepared baking sheet.

Use your fingers or the bottom of a glass to gently flatten each dough ball. This helps them bake evenly and get the classic sugar cookie shape.

Bake the cookies in the preheated oven for 10–12 minutes. Edges should be lightly golden. Centers may look soft; they will firm as they cool.

Remove cookies from the oven. Let them cool on the baking sheet for 5 minutes, then transfer to a cooling rack. This prevents overbaking and keeps them soft.