Preheat your oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment paper.

Cream together the softened butter, light brown sugar, and white sugar in a large mixing bowl using an electric mixer for about 3-4 minutes.

Add the eggs and vanilla extract to the creamed mixture, beating on low speed until fully combined.

In another bowl, whisk together the all-purpose flour, baking powder, salt, and rolled oats. Gradually mix this dry mixture into the wet ingredients until combined.

Scoop out ⅔ of the oat mixture and press it evenly into the bottom of the prepared pan.

In a microwave-safe bowl, combine the semi-sweet chocolate chips and sweetened condensed milk, microwaving in 30-second intervals until smooth.

Pour the melted fudge evenly over the pressed oat base, spreading it gently to the edges.

Using the remaining oat mixture, drop spoonfuls on top of the fudge layer.

Bake for about 45 minutes until the edges are golden brown and the center is slightly jiggly.

Allow the bars to cool completely in the pan for about 1-2 hours before slicing.