Place the Lemon or Golden Oreos in a food processor and pulse until very fine; alternatively, put cookies in a large resealable plastic bag and crush with a rolling pin.
Transfer the crushed cookies to a bowl or the bag and pour in the melted butter; mix or shake until crumbs are evenly moistened.
Press the buttered cookie crumbs firmly and evenly into the bottom of a 9 x 13-inch baking dish to form the crust.
In a medium bowl, use a hand mixer to beat the powdered sugar, softened cream cheese, and softened 1/2 cup butter until smooth.
Fold in half of the whipped topping into the cream cheese mixture until combined, then spread this layer evenly over the cookie crust.
In a separate bowl, whisk the lemon instant pudding mixes with 3 cups milk until the pudding thickens (about a few minutes).
Pour the thickened lemon pudding over the cream cheese layer and smooth the top, then chill in the refrigerator for at least 5 minutes to set.
Spread the remaining whipped topping over the pudding layer, refrigerate at least 1 hour before serving, and garnish with lemon slices.