Heat the oven to 300 °F and line a large rimmed baking sheet with parchment paper. The parchment keeps the sticky mixture from grabbing the pan and makes cleanup much easier.

Pulse the almonds, pecans, shredded coconut, and pumpkin seeds in a food processor until the mixture looks coarse with some larger pieces still visible, then move it to a large bowl and stir in the granulated sweetener and vanilla whey protein powder. Stop before the nuts turn to flour, because visible bits create better texture and sturdier clusters.

Melt the peanut butter and butter together in a microwave-safe bowl, pour that over the dry mixture, and toss until coated before stirring in the water. Once the water goes in, the mixture should start clumping and feel damp enough to press together.

Spread the mixture evenly on the prepared baking sheet, press it down firmly with your hands, and bake for 30 minutes, stirring halfway through and pressing it down again. By the end, it should look lightly golden, smell deeply toasted, and still feel a bit soft while hot.

Let the granola cool completely on the pan, then break up the large pieces with your hands. The clusters firm up dramatically as they cool, so patience gives you the best crunch.