Place the pecans, macadamia nuts and almonds in a food processor, and pulse a few times until you have a mix of fine nut powder and some larger nut chunks. Variety in size is good. Add the rest of the dry ingredients.
Melt the peanut butter a little bit — 15 seconds in the microwave should do it.
Add the eggs, peanut butter, and almond milk. Mix until thoroughly blended.
Pour the batter into a greased non-stick or parchment paper-lined 8″ square pan. Smooth it out so it even all the way to the edges. Bake at 350° for 30 minutes.
Fresh out of the oven, cut into rectangles. Store in an airtight container.