Preheat oven to 325. Spray the sides of the 9.5-inch springform pan with nonstick baking spray. Wrap the sides of the pan with a strip of parchment paper.
In a food processor, pulse the peanut butter cookies until crumbs form.
Add the melted butter and pulse until the crumbs are coated with butter.
Press the crumbs firmly into the bottom of a prepared pan.
Place in the fridge to chill for 15 minutes or until firm. Work on the cheesecake batter.
In a large mixing bowl, add in the cream cheese and peanut butter. Beat with a hand mixer on medium until creamy.
Add the granulated sugar and brown sugar and beat until completely incorporated. Scrape the sides and bottom of the bowl.
Add in the vanilla extract and then the eggs one at a time. Beat in each egg completely before adding the next. Scrape down the bowl after adding each egg.
Add in the sour cream and heavy cream. Mix until incorporated.
Fold in the M&M's and mini chocolate chips.
Just before adding the cheesecake mixture, wrap the outside of the springform pan with two layers of heavy-duty tin foil. I double wrap it to prevent the water from leaking in. Pour the cheesecake filling into the crust.
Place the springform pan in a larger baking pan. Fill the outer pan with about an inch of water.
Place in the oven at 325 degrees and let bake for 1 hour 35 minutes or until done. The top of the cheesecake will be brown. To make sure the cheesecake is done, give it a wiggle. If it slightly jiggles in JUST the middle like jello, then it's done. If it jiggles all over, it needs to bake longer. Let it cool in the oven for 1 to 2 hours until it reaches room temperature and then place in the fridge to chill overnight.
In a microwave-safe bowl, add chocolate chips, heavy cream.
Microwave in 30-second intervals and stir afterward. Repeat until the ganache is smooth and completely melted.
Pour about ⅓ to ½ of the ganache on the top of the cheesecake.
Let it rest of the ganache sit at room temperature until it thickens to a spreadable consistency. You can speed up the process by placing it in the fridge. Keep an eye on it.
While the ganache is setting up, decorate the top with the regular sized M&M's. Leave about an inch of space around the edge of the cheesecake for the piped ganache.
Add the remaining ganache into a disposable piping bag fitted with a 1M tip. Pipe swirls on the top of the cheesecake.