Preheat oven to 350° and spray a 9x13 inch baking dish with non-stick spray.
Combine brown sugar, butter, peanut butter and vanilla extract in an electric mixer. Beat on medium speed to cream mixture until it is light and fluffy.
Next add the eggs, baking powder and salt on low speed. Slowly add the flour and oats, mix until just combined {don't over mix}. Add M&M's, mini chocolate chips and peanut butter chip, mix in by hand or on low speed of the mixer. Add 60% of the dough to the pan and press into the bottom of baking dish {being sure it is in an even layer}.
For the fudge layer, combine the chocolate chips, sweetened condensed milk and butter in a microwave safe bowl. Microwave for 2 minutes, mix and add 30 second intervals until the mixture is smooth. Pour the fudge over the bottom oatmeal layer.
Take the remaining dough and crumble pieces over the entire surface of the fudge. Bake for 30-35 minutes, or until the top is golden brown. Cool completely at room temperature and chill for at least 60 minutes before cutting into squares. Store at room temperature for up to 5 days.