Prepare the brownies.
Preheat oven to 350°F.
Grease a 9x13-inch baking pan and set aside.
In a medium bowl, add flour, baking powder and salt; mix well.
In a separate bowl, add sugar, cocoa powder and butter; mix well.
Add eggs and vanilla, and gently mix until well combined.
With a rubber spatula, add flour mixture to the chocolate mixture.
Stir in milk until well blended.
Pour batter into prepared pan and spread out evenly.
Sprinkle with crushed Thin Mints.
Bake for 15-18 minutes, or until a wooden toothpick inserted near the center comes out clean.
Let cool fully.
Crumble brownies and set aside.
Prepare the pudding.
Whisk milk and pudding together.
When fully mixed, whisk in half-and-half.
Let stand 5 minutes until pudding sets.
To assemble: In a large glass bowl, layer 1/3 of the crumbled brownies, 1/3 of the chocolate pudding, then 1/3 of the whipped topping and sprinkle 1/3 of the crushed Samoa cookies on top.
Repeat with another 2 layers in the same order.
Garnish with 2 Samoa cookies.
Refrigerate for 1 hour before serving.