Lightly spray the bottom and sides of 9-inch springform pan with cooking spray, gently wipe edges with a paper towel. Set aside.
In the bowl of an electric mixer, add the butter and both sugars and beat at medium speed until well combined. Add the peanut butter and mix until well blended. Add the flour and vanilla and mix just until combined. Add the oats and stir until combined (the dough will be thick). Fold in the M&M’s and mini-chocolate chips with a spatula (be careful not to crush the M&M’s). Press the dough into the bottom of the pan to form the crust.
Pour 1 1/2 cups of the whipping cream into the bowl of an electric mixer. Beat on medium-high speed until the cream starts to get bubbly. Slowly add the powdered sugar and continue beating on high speed until stiff peaks form. Set aside.
In another bowl, beat the cream cheese on medium-high speed for 2 to 3 minutes until it’s light and fluffy (you can use a stand mixer or a hand mixer). Slowly add the sugar into the cream cheese with the mixer going. Next add the remaining 2 tablespoons of heavy whipping cream and the vanilla. Continue beating the filling until smooth and creamy. Fold in the mini-chocolate chips. Fold the whipped cream into the cheesecake mixture. Pour the filling into the prepared crust and smooth the top with a spatula. Before you place cheesecake in the freezer, run a flat-edge knife around the edge to help release it slightly from the edges of the pan. Cover with foil and refrigerate 4 to 6 hours (the longer the better),
Combine the whipping cream and powdered and beat until stiff peaks form. Remove the springform pan edge and use a large star tip to pipe on the whipped cream on the outside edges of the cheesecake. Microwave the peanut butter for about 15 seconds then drizzle over the edges of the cheesecake. (I like to put the peanut butter into a small Ziploc bag and then just snip a corner of the bag off). Garnish with additional M&M’s and serve immediately. Refrigerate leftovers.