In a large microwave-safe bowl, melt unsalted butter(½ cup, i.e 1 stick). Stir in granulated sugar(¼ cup) and lightbrown sugar(¾ cup) and mix with a whisk for 1 minute, or until mixture is cooled down.
Add eggs (2 large) and vanilla extract (2 teaspoons) and whisk for 2 minutes until smooth & creamy.
Add baking soda (1 teaspoon) and koshersalt (½ teaspoon) and stir in.