Preheat oven to 350°F (175°C). Line a 9-inch springform pan with parchment paper and spray the sides with nonstick spray.
Stir together melted butter and cocoa powder. Set aside.
Beat sugar, eggs, and vanilla extract until combined. Mix in cocoa mixture.
Add flour, salt, and baking powder. Mix until just combined, then fold in chocolate chunks.
Spread brownie batter evenly in prepared pan. Bake for 25 minutes. Cool completely.
Remove brownie from pan, peel off parchment, and place it back into the springform pan.
Beat cream cheese and powdered sugar until smooth and creamy.
Add mint extract and vanilla extract; beat until combined.
Gently fold in 2 cups of Cool Whip. Add green food coloring until desired shade is reached.
Chop 15 mint cookies and fold into cheesecake mixture.
Spread cheesecake mixture evenly over cooled brownie. Refrigerate for at least 1 hour.
Heat chocolate chips and heavy cream in microwave for 30 seconds. Stir until smooth and creamy.
Let ganache cool slightly, then spread evenly over cheesecake.
Cut remaining cookies in half and place around the edge of the cake.
Pipe remaining Cool Whip between cookies and top with green sprinkles.