Set your oven to 180°C (350°F). Line a baking sheet with parchment paper. This prevents sticking and ensures even baking.

In a saucepan, melt butter over low heat. Add granulated sugar and brown sugar. Stir until smooth and combined.

Remove the saucepan from heat. Let it cool slightly. Add vanilla extract and the beaten egg. Stir well to combine.

In a bowl, mix flour, baking soda, salt and rolled oats. If using nuts, add them now.

Pour the butter mixture into the flour and oats. Stir until you get a thick, sticky dough.

Fold in chocolate chips or white chocolate chunks. Mix evenly to distribute chocolate in every bite.

Using a spoon, drop small mounds of dough onto the prepared baking sheet. Leave space between each cookie.

Place in the preheated oven for 12–15 minutes. Bake until edges are golden brown. The center may look soft but will firm up.

Remove cookies from oven. Let them cool for 5 minutes on the sheet. Transfer to a cooling rack to cool completely.

Once cooled, serve immediately. Store extra cookies in an airtight container to maintain their crisp texture.