Peanut Butter Monster Cookie Dream Bars

Preheat the oven to 375 degrees F (190 degrees C).

Stir oatmeal, flour, butter, brown sugar, baking soda, and salt together in a bowl. Reserve 1 1/2 cups of crumb mixture. Spread remaining mixture into a 9x13-inch baking pan.

Bake in the preheated oven until crust is lightly browned, about 12 minutes. Remove crust; leave oven on.

Mix sweetened condensed milk and peanut butter together in a bowl. Spread over the baked crust. Sprinkle the reserved crumb mixture and milk chocolate pieces on top.

Bake in the preheated oven until golden brown, about 20 minutes.