Start by stirring together the peanut butter and sweetener in a medium mixing bowl. Mix slowly at first, then continue until the texture becomes smooth and creamy with no visible streaks of sweetener. If the peanut butter feels too thick or stiff, warm it in the microwave for about 10–15 seconds to soften it and make mixing easier.

Add the protein powder gradually instead of dumping it in all at once. Stir after each addition so it blends evenly into the peanut butter mixture. The mixture will begin to thicken — this is exactly what you want. If the mixture becomes too firm to mix easily, add a teaspoon of milk and continue stirring until it loosens slightly but still remains thick and moldable.

Gently fold in the oats using a spatula or spoon. Mix until everything is fully combined and the oats are evenly coated. The texture should be dense and similar to cookie dough. If it feels sticky or too soft, sprinkle in a little more oats. If it feels dry or crumbly, add a tiny splash of milk or a small amount of peanut butter and mix again until smooth and cohesive.

Line a loaf pan or shallow tray with parchment paper, making sure there’s enough overhang to lift the bars out later. Scoop the mixture into the lined tray, then press it down firmly using the back of a spoon, a spatula, or clean hands. The more firmly it's packed, the better it will hold its shape once sliced.

Place the tray in the refrigerator and let the mixture chill for at least one hour. This step helps the bars firm up and allows the oats to soften slightly while absorbing moisture. If you're in a hurry, you can place the tray in the freezer for about 20–30 minutes instead.

Once fully chilled and firm, lift the mixture out of the tray using the parchment paper. Transfer it to a cutting board and slice into bars or squares — choose the size based on how you plan to use them. Store the bars in an airtight container in the refrigerator to keep them fresh, firm, and ready to grab whenever you need a quick, protein-rich snack.