Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking sheet.

In a large mixing bowl, combine the softened unsalted butter, eggs, and pistachio instant pudding mix until smooth.

Gradually add the sugar cookie mix, folding in gently until just combined.

Transfer the dough to the prepared baking sheet and press it evenly across the surface.

Bake for 18–22 minutes, until the edges are light golden brown and the center is soft.

Let the cookie bars cool in the pan for about 10 minutes, then transfer them to a wire rack to cool completely for at least 30 minutes.

Optionally, drizzle melted chocolate over the cooled cookie bars for added indulgence.