In a large mixing bowl, combine the softened cream cheese, softened butter, and creamy peanut butter. Use a hand mixer or a stand mixer on medium speed to beat the ingredients together until the mixture is completely smooth and light in color. This usually takes about 2 to 3 minutes.
Turn the mixer to low speed and gradually add the powdered sugar and brown sugar. Once the sugar is mostly incorporated, add the vanilla extract. Increase the speed to medium and beat for another minute until the mixture is fluffy and there are no visible lumps of sugar.
Remove the mixer and use a large rubber spatula for this step. Gently fold in the quick-cooking oats until they are evenly distributed. Next, fold in the mini chocolate chips and the mini M&Ms. Be careful not to over-mix, as you want the candies to remain whole and the colors to stay bright.
Transfer the dip to a serving bowl. If you have time, cover the bowl with plastic wrap and refrigerate for at least 30 minutes. Chilling helps the flavors meld and allows the oats to soften slightly. Top with a few extra M&Ms before serving alongside your favorite dippers.