Arrange the peanut butter sandwich cookies evenly across the bottom of a 9x13-inch baking dish, making sure the entire base is covered. If there are small empty spaces around the edges, gently break a few cookies into smaller pieces and fit them into the gaps. Press the cookies down lightly with your hands so they create a stable crust layer that will soften beautifully once chilled.
Place the softened cream cheese into a large mixing bowl and beat it using a hand mixer until completely smooth, creamy, and fluffy. Continue mixing for 1–2 minutes to remove all lumps, as this step helps create a silky cheesecake-style filling with the best texture.
Add the Greek yogurt, natural peanut butter, vanilla protein powder, powdered sweetener, and vanilla extract directly into the bowl with the cream cheese. Mix everything together thoroughly until the mixture becomes thick, smooth, creamy, and evenly combined. Scrape down the sides of the bowl occasionally to ensure all ingredients are fully incorporated without streaks.
Using a silicone spatula, gently fold the whipped topping into the peanut butter mixture. Stir slowly with light motions rather than aggressively mixing so the filling stays fluffy, airy, and mousse-like. Continue folding just until no white streaks remain.
Spoon the peanut butter cheesecake filling over the cookie crust and carefully spread it into an even layer using the back of a spoon or an offset spatula. Smooth the surface neatly so the next layer sits evenly on top.
Transfer the dish into the refrigerator while preparing the chocolate pudding layer. Chilling the peanut butter layer briefly helps it firm up slightly, which keeps the dessert layers clean and distinct.
In a separate large bowl, whisk together the sugar-free chocolate pudding mix, high-protein milk, and chocolate protein powder. Continue whisking for several minutes until the pudding thickens into a rich, creamy consistency with no dry powder remaining. The mixture should look smooth, glossy, and thick enough to spread easily.
Add the crushed peanut butter cookies into the pudding mixture and gently fold them in until evenly distributed throughout the chocolate layer. The crushed cookies add texture, crunch, and extra peanut butter flavor to every bite.
Remove the chilled baking dish from the refrigerator and carefully spread the chocolate pudding mixture over the peanut butter cheesecake layer. Use gentle motions while spreading so the layers remain separate and visually defined rather than mixing together.
Place the dessert back into the refrigerator for about 10 minutes to help the pudding layer firm up slightly before adding the topping. This quick chill helps create cleaner layers and prevents the whipped topping from sinking.
Spread the remaining whipped topping evenly across the top of the dessert, creating a smooth and fluffy finish. Take your time smoothing the surface for a beautiful presentation.
Sprinkle the chopped peanut butter cups evenly over the whipped topping, making sure each serving will have plenty of chocolate-peanut butter pieces on top. For extra texture, lightly press a few pieces into the topping while leaving others visible on the surface.
Place the peanut butter into a microwave-safe bowl and heat it in short intervals until melted and smooth. Using a spoon, drizzle the warm peanut butter across the top of the dessert in thin lines for a bakery-style finish.
If desired, drizzle melted dark chocolate over the top as an additional garnish. The chocolate adds richness and creates an even more indulgent Reese’s-inspired flavor combination.
Cover the dish carefully and refrigerate the dessert for at least 4 hours, although overnight chilling is highly recommended for the best texture and flavor. During this time, the layers will set properly and the cookies will soften slightly into a cake-like consistency.
Once fully chilled, slice the dessert into even squares using a sharp knife. Wipe the knife clean between slices for neat, clean layers. Serve the peanut butter lasagna cold straight from the refrigerator and enjoy every creamy, chocolatey, protein-packed bite.