Preheat the oven to 350°F (175°C). Grease a baking pan or line it with parchment paper.

In a mixing bowl, combine rolled oats, flour, brown sugar, and granulated sugar.

Stir in melted butter, egg, and vanilla extract until well combined.

Fold in chocolate chips, nuts, and dried fruit if using.

Spread the mixture evenly in the prepared baking pan.

Bake in the preheated oven for 20-25 minutes, or until the edges are golden brown.

Remove from the oven and allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

Once cooled, cut into bars and serve.