Preheat your oven to 350°F (175°C) and grease a 9x9 inch baking pan.

In a large bowl, mix the melted butter and sugar until well combined.

Add the eggs one at a time, beating well after each addition.

Stir in vanilla extract and Baileys Irish Cream.

In another bowl, whisk together the flour, cocoa powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing just until combined.

Pour the batter into the prepared baking pan and spread evenly.

Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out with a few moist crumbs.

Let the brownies cool in the pan on a wire rack before cutting into squares.