Dump the batter into the pan and use a rubber spatula to spread evenly into all edges of the pan.

Bake for 20-22 minutes or until a toothpick inserted in the center comes out clean. Allow brownies to cool completely before slicing into cubes.

In the well-chilled bowl of an electric stand mixer fitted with a whisk attachment, whip the heavy cream and powdered sugar together until stiff peaks form. Transfer whipped cream to another bowl and place in refrigerator to keep chilled.

Return bowl to mixer. Switch whisk attachment out and replace with paddle attachment. Beat cream cheese until smooth. Gradually stir in the milk, about 1/4 cup at a time, scraping down the sides of the bowl as needed. Once all milk has been added, switch back to whisk attachment and add the pudding mix. Whisk on high for 2 minutes until mixture is smooth and thickened.

Add 1 cup of the whipped cream to the bowl and mix thoroughly. Remove bowl from mixer and use a rubber spatula to gently fold about 1/2 of the whipped cream into the pudding mixture.

Place a layer of brownie cubes in the bottom of a trifle dish*. You'll use half of the brownies. Then pour half of the filling into the trifle dish and spread out evenly. Evenly scatter the chopped candy bars on top of the filling. Add another layer of brownie cubes (using up the last half), followed by the rest of the filling. Top with the reserved whipped cream, spreading evenly. Sprinkle crushed Oreos evenly over whipped cream, making sure to cover up any white that might peek through. Garnish with chocolate tombstones and Halloween sprinkles, if desired.