Preheat your oven to 350°F (175°C). This ensures that your donuts bake evenly.
Grease your donut pan with a little oil or spray to prevent sticking. If you’re using a silicone pan, this step may not be necessary.
In a mixing bowl, whisk together the flour, chocolate protein powder, cocoa powder, baking powder, and salt until well combined.
In another bowl, combine the peanut butter, water, yogurt or mashed banana, and maple syrup or honey. Mix until smooth and creamy.
Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix; a few lumps are okay.
Spoon the batter into the prepared donut pan, filling each cavity about 3/4 full. This allows room for the donuts to rise without overflowing.
Place the pan in the preheated oven and bake for 12-15 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, let the donuts cool in the pan for about 5 minutes before transferring them to a cooling rack to cool completely.